Section 351 ETF Exchanges: How They Work and Who Qualifies

For many investors, the math of rebalancing a taxable portfolio has quietly become irrational. A position accumulated over decades, or a diversified portfolio that has simply grown, may carry a cost basis that represents a fraction of its current market value. To rebalance meaningfully, the investor must sell. Selling means realizing gains. And realizing gains, for a high-income taxpayer in a high-tax state, can mean surrendering 30% or more of the gain to combined federal and state taxes before a dollar of the proceeds is reinvested, though the exact rate depends on the individual's specific tax situation.

The result is a population of investors who are simultaneously over-concentrated and under-diversified. Not because they lack awareness or good advice, but because the cost of change is genuinely prohibitive. Advisors refer to this as being locked in a position, and it is one of the most persistent structural problems in taxable wealth management.

Section 351 of the Internal Revenue Code offers one well-established answer to this problem. It is not a loophole or a grey-area maneuver. It is a provision that has existed in the tax code for decades, codified and regulated by the IRS, and now accessible to a broader range of investors and advisors than at any point in its history. This primer is designed to explain it clearly and accurately, covering the mechanics, eligibility, benefits, risks, and process, written for the advisors and accredited investors for whom it may be relevant.

Nothing in this document constitutes tax, legal, or investment advice. The analysis of any specific investor's eligibility and suitability for a Section 351 exchange requires engagement with qualified tax counsel and financial advisors familiar with the investor's complete financial situation.

What Is a Section 351 Exchange?

Section 351(a) of the Internal Revenue Code provides that no gain or loss is recognized when property is transferred to a corporation by one or more persons solely in exchange for stock in that corporation, provided those persons collectively control at least 80% of the corporation immediately after the exchange. [1]

Applied to portfolio management, this works as follows: an investor contributes a portfolio of appreciated securities, in-kind and without selling, to a newly formed Exchange-Traded Fund (ETF). In exchange, the investor receives shares of that ETF. The contribution is not a taxable event. The investor's existing cost basis carries over to the received ETF shares, as does the original holding period.

The gain embedded in the contributed securities is deferred, not eliminated. Taxes will eventually be owed when the ETF shares are sold. But the deferral itself creates real economic value, both through the time value of capital that remains invested rather than paid to the IRS, and through the structural tax efficiency of the ETF wrapper, which can meaningfully reduce gain recognition on an ongoing basis after the initial contribution.

The closest analogy in US tax law is the 1031 exchange, which allows real estate investors to defer capital gains by rolling the proceeds of a property sale into a like-kind replacement property. Section 351 is, in conceptual terms, its counterpart for diversified securities portfolios: a mechanism to move from individual holdings into an aggregated fund structure without triggering recognition. [2]

Why This Strategy Is Gaining Attention Now

Section 351 has been part of the Internal Revenue Code for many years, but its application to individual investor ETF seeding has accelerated materially in the 2020s. Historically, the cost and complexity of launching a registered ETF meant this approach was effectively limited to large family offices and institutional asset managers. The emergence of specialized ETF infrastructure providers, improved custodial technology, and a growing body of advisor and investor education has lowered those barriers significantly. A 2026 analysis catalogued approximately $8.7 billion in individual investor seed assets contributed across approximately 39 ETFs launched between 2021 and 2025 using Section 351 structures, a figure that reflects a genuine shift from niche institutional strategy to an emerging advisory tool. [3]

Who This Strategy Is Built For

The Investor Profile

Section 351 is most relevant for investors who meet a specific set of circumstances: a diversified taxable portfolio with substantial unrealized gains built over many years of equity market participation; a desire to rebalance, reallocate, or transition into a more appropriate long-term strategy, constrained by the tax cost of doing so through traditional means; an investment horizon long enough to benefit from gain deferral, ideally measured in decades; and a genuine intent to hold an ETF as a long-term investment, not as a vehicle for near-term disposition.

The strategy carries minimum contribution requirements that vary by ETF sponsor and custodial platform. These minimums are set by the ETF program, not by the IRS, and differ significantly across programs. Some sponsors have set per-account contribution minimums as low as $150,000 for accounts held at specific custodians, while others require $1 million or more depending on the program and platform. Advisors should confirm the applicable minimum directly with the ETF sponsor before engaging a client in the process, as these thresholds change as the market for 351-seeded ETFs continues to develop.

The Advisor's Dilemma

Financial advisors face a structurally difficult situation with a specific class of client: those whose portfolios have been managed with disciplined tax-loss harvesting over many years, to the point where there are no losses remaining to offset gains. At that juncture, the traditional tax management toolkit is exhausted. Meaningful rebalancing generates a material tax bill. The advisor knows the portfolio is not positioned optimally; the client knows it too; but neither party wants to absorb the consequence of addressing it.

This creates a stalemate that can persist for years, leaving clients in allocations that no longer reflect their risk tolerance, time horizon, or investment objectives. Not because of any failure of advice, but because of the structural tax friction inherent in a well-appreciated taxable portfolio. Section 351 breaks that stalemate. For the right client, in the right circumstances, it allows the portfolio to be repositioned into a professionally managed ETF without triggering the capital gains event that has been preventing the transition.

Institutional and Family Office Use Cases

For institutional investors and family offices managing significant equity portfolios across multiple accounts and entity types, Section 351 offers additional utility. The ability to consolidate dispersed holdings across individual accounts, trusts, and partnership entities into a single ETF structure can reduce reporting complexity, improve portfolio governance, and create a more coherent long-term investment framework. For multi-generational family offices in particular, the simplification of moving from hundreds of individual positions to a single fund holding can be administratively significant, and the ongoing tax efficiency of the ETF wrapper supports long-duration wealth management objectives. [4]

How It Works: The Mechanics

The In-Kind Contribution

The foundational transaction is conceptually simple. The investor, referred to as the transferor, contributes a portfolio of eligible securities to a newly formed ETF in exchange for shares of that fund. The contribution is made in-kind: securities move directly from the investor's custodial account to the ETF's custodian via the Depository Trust Company (DTC) without being sold. Because no sale occurs, no taxable event is recognized at the time of transfer.

The ETF inherits those securities with a carryover basis, which is the same cost basis the contributing investor originally held, along with the same holding period. The investor receives ETF shares at the same carryover basis and holding period. Future gains or losses on those shares will be measured from the original cost basis when shares are eventually sold.

The Control Requirement

For non-recognition treatment to apply, the contributing investors must collectively own at least 80% of the ETF's voting stock immediately after the contribution. [1] Because the ETF is newly formed specifically to receive the in-kind contribution, this requirement is generally met without difficulty, as the contributing investors own substantially all of the fund at launch. Section 351 seeding is effectively a one-time contribution event. After launch, investors who purchase ETF shares on the open exchange are acquiring them through ordinary market transactions, not contributing assets via Section 351.

The Diversification Requirements

The IRS imposes diversification tests to ensure that the non-recognition treatment under Section 351 is not used to make tax-free transfers of highly concentrated, undiversified portfolios into an investment company structure. Under Treasury Regulation Section 1.351-1(c)(6), a contributing portfolio is considered sufficiently diversified and therefore eligible if no single issuer represents more than 25% of the total value of the contributed portfolio, and the five largest issuers collectively represent no more than 50% of total portfolio value. [1]

For these tests, cash, mutual funds, government securities, and certain short-term instruments are generally excluded from the calculation. ETFs held within the contributing portfolio are assessed on a look-through basis: the underlying holdings of the ETF are evaluated individually against the 25% and 50% thresholds, not the ETF itself as a single security. A well-managed diversified equity portfolio of 15 to 20 or more positions will typically satisfy these tests without difficulty.

Tax Consequences

The ETF has no taxable gain or loss as a result of receiving the contributed securities. It carries over both the basis and holding period of each security contributed. A formal tax opinion from qualified tax counsel is issued upon completion of the transaction, confirming that the contribution satisfied Section 351 requirements. This opinion is a material piece of documentation for both the advisor and the contributing investors.

The ETF Structural Advantage: Ongoing Tax Efficiency

The initial deferral of capital gains at the time of contribution is significant, but it represents only part of the tax story. The ETF wrapper provides meaningful ongoing tax efficiency that distinguishes it from separately managed accounts and mutual funds, advantages that persist long after the initial seeding event.

The In-Kind Redemption Mechanism

When shareholders redeem interests in a mutual fund, the fund manager must typically sell underlying securities to raise cash. Those sales generate realized capital gains that are distributed to all remaining shareholders, including those who did not sell and may have experienced negative returns on their investment. ETF shareholders, by contrast, sell their shares to other market participants on the open exchange. The fund itself has no obligation to sell securities or realize gains to accommodate that redemption.

At an institutional scale, large investors (referred to as authorized participants) redeem ETF shares through an in-kind mechanism: they receive a basket of the fund's underlying securities rather than cash. This process allows the ETF to distribute its lowest-cost-basis tax lots to redeeming parties, effectively removing embedded gains from the fund's portfolio without a taxable sale. This treatment is protected under Section 852(b)(6) of the Internal Revenue Code. [1] The cumulative effect, by way of example, is that ETFs using in-kind redemptions distributed capital gains far less frequently than mutual funds in 2024, with roughly 5% of ETFs making capital gains distributions compared to 43% of mutual funds, according to Morningstar.

Management Fee Treatment

Within an ETF, management fees are deducted directly from fund assets and are reflected in the fund's net asset value. This treatment effectively embeds the fee in the cost basis calculation, which can create a modest tax efficiency relative to separately billed SMA fees, which are generally not deductible for individual taxpayers under current law. [4]

Benefits by Audience

For Accredited Investors

Tax deferral without lockup. Unlike exchange funds, which offer similar deferral but require a seven-year holding period and restrict access during that window, ETF shares received in a Section 351 exchange are freely tradeable on the open exchange from the day of fund launch.

Diversification without the tax bill. A portfolio that has been locked by its embedded tax liability can be repositioned into a professionally managed, diversified ETF without triggering immediate capital gains recognition.

Cleaner tax reporting. ETF investors receive a standard 1099 rather than a K-1. Compared to exchange funds structured as limited partnerships, the simplicity of ETF tax reporting is a genuine quality-of-life benefit for investors and their accountants.

Compounding preservation. Capital that would otherwise be paid to the IRS in a traditional rebalancing remains invested. On a meaningful portfolio over a multi-decade investment horizon, the compounding value of that retained capital may be significant, though outcomes will vary based on individual circumstances and market conditions.

For Financial Advisors

Section 351 is, from the advisor's perspective, primarily a problem-solving tool. It addresses one of the most stubborn structural challenges in taxable wealth management: the client with a fully appreciated, fully harvested portfolio who wants to reallocate but cannot afford the tax cost through traditional means. For advisors who have invested in understanding and executing this strategy competently, it represents a meaningful practice differentiator. The ability to offer a credible path through a problem that most advisors simply defer or work around is valuable to the client population for whom it is relevant.

The strategy also supports AUM consolidation and retention. Appreciated positions that sit stuck in an account, often because the client is reluctant to consolidate with a single advisor due to the tax cost of repositioning, become addressable through a mechanism that removes the friction. This can facilitate deeper, more comprehensive advisory relationships around a client's full balance sheet.

For Institutions and Family Offices

For larger institutions and family offices managing equity portfolios across multiple accounts, legal entities, and beneficiaries, the operational consolidation benefits of Section 351 can be as significant as the tax benefits. Replacing dozens or hundreds of individual managed accounts with a single ETF holding simplifies reporting, portfolio monitoring, rebalancing, and compliance oversight, without generating a taxable event at the time of transition.

Section 351 vs. The Alternatives

Advisors considering Section 351 for a client should understand how it compares to other tax management tools that address similar problems.

Exchange Funds are the closest structural analog. Both allow investors to contribute appreciated securities to a pooled vehicle and defer capital gains recognition. The key differences: exchange funds typically require a minimum seven-year holding period before investors can receive their pro-rata share of the fund's diversified holdings; access is restricted during that period; exchange fund interests are generally structured as limited partnership interests, generating K-1 tax documents; and dividends paid by underlying securities may be restricted in some structures. For investors who need liquidity, prefer simpler tax reporting, or are not comfortable with a seven-year lockup, Section 351 into an ETF is generally more flexible.

Charitable vehicles such as donor-advised funds and charitable remainder trusts allow investors to contribute appreciated securities, avoid capital gains at contribution, and receive a charitable deduction. These tools are excellent for investors with philanthropic intent. For investors seeking to preserve wealth for themselves or their heirs rather than directing it to charity, they are not substitutes.

Tax-loss harvesting is a valuable technique, but its capacity is finite. A portfolio that has been systematically harvested for years may have no remaining loss capacity, as every position is in a gain. Section 351 is particularly relevant precisely in that situation, offering a path forward when the conventional toolkit no longer applies.

Gifting and estate strategies such as gifting to family members in lower brackets, or anticipating a step-up in basis at death, can be effective components of a comprehensive estate plan. These are ownership-transfer strategies, however, not portfolio reallocation tools. They do not address the investor's need to transition from individual securities into a different investment strategy within their own taxable account.

What Qualifies and What Doesn't

Eligible Asset Classes

The following asset types are generally eligible for in-kind contribution in a Section 351 exchange, subject to consistency with the receiving ETF's investment objective: US-listed equities and American Depositary Receipts (ADRs); US-listed ETFs, assessed on a look-through basis for diversification purposes; US-listed foreign equity ETFs; certain fixed income ETFs; and closed-end funds listed on US exchanges.

Generally Not Eligible

The following are generally not eligible: cash and cash equivalents; mutual funds (cannot be transferred in-kind); US Treasury and government bonds (excluded from diversification calculations); restricted stock and unvested equity compensation; derivative securities; private equity, private REITs, and illiquid private investments; OTC securities in most circumstances; securities held in ERISA accounts without a Department of Labor exemption; and assets contributed by foreign investors.

Entity Eligibility

Individuals, revocable and irrevocable trusts, partnerships, limited partnerships, foundations, and most tax-exempt organizations are generally eligible to participate as transferors. IRAs may participate with additional diligence. C corporations present a significant complication: when a C corporation contributes assets to a Regulated Investment Company such as an ETF, the fund may be subject to a built-in gains tax on those assets if disposed of within five years of contribution. This makes C corporation participation generally inadvisable. Foreign investors are generally excluded from participating as transferors. [4]

Risks, Limitations, and Important Considerations

Tax deferral is not tax elimination. The investor's original cost basis carries into the ETF shares received. When those shares are eventually sold, the full embedded gain, plus any appreciation accrued within the ETF after contribution, will be recognized and taxed. The economic case for Section 351 rests on the value of deferral and the ongoing structural tax efficiency of the ETF wrapper, not on any form of permanent tax relief.

The step-transaction doctrine. The IRS applies this doctrine to evaluate whether a series of individually permissible steps amounts to a single transaction with a tax-avoidance purpose. A Section 351 contribution followed quickly by a sale of the received ETF shares, for example, could be challenged as a disguised taxable sale with no genuine business purpose. [1] The transaction must be genuine. Investors must have a bona fide intent to hold the ETF as a long-term investment. This requirement is substantive, not procedural, and is reflected in the formal representations that contributing parties make in writing as part of the transaction.

Market and strategy risk. A Section 351 exchange is not purely a tax transaction; it is an investment decision. The investor is contributing their securities to a specific ETF with a defined investment strategy. Once the contribution is made, the portfolio is managed according to the fund's prospectus, not according to the investor's prior individual preferences.

One-time event. The Section 351 seeding mechanism is not an ongoing contribution vehicle. After the initial fund launch, investors who purchase ETF shares on the open market do so through ordinary transactions. The tax-deferred contribution cannot be replicated for the same ETF after launch.

Minimum scale and cost. Start-up costs for a 351-seeded ETF are typically higher than for a conventional ETF launch. Most practitioners recommend approximately $50 million in eligible contributing assets as the practical minimum threshold for economic justification. [4]

The requirement for qualified counsel. A properly executed Section 351 exchange requires a formal tax opinion from qualified tax counsel, coordination across the ETF sponsor, custodians, and fund administrators. The transaction is not appropriate for investors or advisors seeking a simple, do-it-yourself approach, and the tax and legal analysis must be tailored to each participant's specific circumstances.

The Process: A High-Level Roadmap

A Section 351 ETF seeding typically runs approximately 12 weeks from initial planning to fund launch, organized across three phases. For funds where a pre-launch marketing period is recommended, total elapsed time from initial planning to the first day of trading will be longer.

Phase 1: Pre-Launch Preparation. Initial planning involves confirming participant eligibility, reviewing portfolio composition against diversification requirements, engaging tax counsel, and selecting an ETF sponsor with experience in 351 transactions. Each participating investor must execute two key documents: a Letter of Authorization directing their custodian to initiate the in-kind securities transfer, and a Transferor Representation Agreement in which the investor makes formal legal representations about their eligibility, intent, and the nature of their contributed assets. Approximately four weeks before launch, tax lot information is finalized, a trading freeze is imposed on all contributing portfolios, and any securities that fail diversification tests are returned to the contributing account and excluded from the contribution.

Phase 2: Final Pre-Launch Execution. Tax lot data is reviewed and confirmed by the ETF's fund administrator. Securities are transferred in-kind via DTC from each contributing custodian to the ETF's custodian. A final diversification check is performed using closing market prices on the night before launch. The initial NAV of the ETF is established, and ETF shares are allocated to each contributing investor based on the market value of their contribution.

Phase 3: Marketing Period, Launch, and Post-Launch. Once the ETF registration becomes effective with the SEC, a marketing period of 3 to 4 months is generally recommended before the fund begins trading. This window allows for investor education, advisor onboarding, and assessment of seed capital sufficiency, all of which contribute to a more successful launch and stronger ongoing liquidity in the fund. At the end of the marketing period, the ETF begins trading on exchange. ETF shares are distributed back to each contributing investor's account, typically within three business days of launch. Cost basis information is transmitted to custodians and brokers. The fund's tax counsel issues the final tax opinion confirming Section 351 compliance. Contributing investors who held 5% or more of the total ETF at seeding receive additional documentation for their tax returns. [4]

Closing: A Strategy Worth Understanding

Section 351 is not new, and it is not exotic. It is a provision of the Internal Revenue Code designed to allow investors to transition appreciated portfolios into corporate structures, including investment companies like ETFs, without the tax friction that would otherwise make such transitions prohibitively costly.

What has changed in recent years is access. The infrastructure needed to execute a Section 351 ETF seeding: ETF sponsors, custodial technology, legal frameworks, and advisor education, has matured to the point where the strategy is genuinely viable for a broader class of investors and advisors than ever before. What was once the exclusive province of the largest family offices is increasingly within reach of well-advised, high-net-worth individuals with the right portfolio characteristics.

The strategy is not appropriate for everyone. It requires a specific investor profile, a genuine long-term investment purpose, a minimum asset base, and a team of qualified professionals to execute it properly. The risks, including the reality that deferred gains are not eliminated gains, and that IRS scrutiny of the business purpose requirement is real, must be understood and accounted for.

For the investor who has been locked in an appreciated portfolio, watching their allocation drift from optimal because the cost of change is too high, Section 351 offers a legitimate and well-established path forward. For the advisor who has watched that situation persist for years without a credible answer, it is a meaningful addition to the planning toolkit. Stance Capital has worked with financial advisors on Section 351 transactions in the past. As with any tax strategy of this complexity, the decisions involved require qualified tax, legal, and financial guidance tailored to each individual's specific circumstances. This primer is intended as educational context only.

‍Frequently Asked Questions

What is a Section 351 exchange?

A Section 351 exchange is a transaction under Section 351(a) of the Internal Revenue Code in which one or more investors contribute a portfolio of appreciated securities to a newly formed ETF in exchange for shares of that fund. If the transaction meets the requirements of Section 351, including the control requirement and diversification tests, no gain or loss is recognized at the time of contribution. The investor's cost basis and holding period carry over to the ETF shares received.

Are capital gains eliminated in a Section 351 exchange?

No. Capital gains are deferred, not eliminated. The investor's original cost basis carries forward into the ETF shares. When those shares are eventually sold, the accumulated gain, plus any additional appreciation within the ETF, will be recognized and taxed. The economic benefit lies in the value of deferral and the ETF's ongoing structural tax efficiency.

What is the minimum portfolio size to consider a Section 351 exchange?

Most practitioners and ETF infrastructure providers recommend a minimum of approximately $50 million in eligible contributing assets for a Section 351 transaction to be economically practical, given the legal, compliance, and operational costs involved. [4]

What types of assets can be contributed?

Eligible assets generally include US-listed equities, ADRs, US-listed ETFs (on a look-through basis), listed fixed income ETFs, and closed-end funds, provided they are consistent with the receiving ETF's investment objective. Cash, mutual funds, government bonds, restricted stock, derivatives, private securities, and OTC securities are generally not eligible.

How is a Section 351 exchange different from selling and reinvesting?

In a traditional sell-and-reinvest rebalancing, the investor sells appreciated securities, recognizes capital gains, pays the resulting tax, and reinvests the after-tax proceeds. In a Section 351 exchange, the investor contributes the appreciated securities directly to the ETF in-kind. No sale occurs, no gain is recognized at the time of contribution, and the full pre-tax value of the portfolio transitions into the ETF structure.

How does Section 351 compare to an exchange fund?

Both mechanisms allow investors to contribute appreciated securities and defer capital gains recognition. Exchange funds generally require a seven-year holding period and restrict liquidity during that window; ETF shares received in a Section 351 exchange are freely tradeable from launch day. Exchange funds typically generate K-1s; ETF shareholders receive 1099 reporting.

Can all types of investors participate?

Not all entity types are eligible. Individuals, trusts, partnerships, foundations, and most tax-exempt organizations are generally eligible. C corporations are generally not eligible due to built-in gains tax complications. Foreign investors are generally excluded. Each participant's eligibility should be reviewed by qualified tax counsel.

How long does the process take?

The core transaction process, from initial planning through fund launch, typically takes approximately 12 weeks. For funds where a pre-launch marketing period is recommended, a 3 to 4 month window between the effective date and the first day of trading is generally advisable, extending the total elapsed time accordingly. Timeline can also vary based on custodian complexity, portfolio composition, and participant count.

Is Section 351 legal and IRS-recognized?

Yes. Section 351 is a codified provision of the Internal Revenue Code that has existed for decades. Treasury Regulation Section 1.351-1(c)(6) specifically governs transfers to investment companies under Section 351. A formal tax opinion from qualified tax counsel is issued with each properly structured transaction confirming compliance with applicable requirements.

What happens to my cost basis after a Section 351 exchange?

Your original cost basis in the contributed securities carries over to the ETF shares you receive. Future appreciation will be taxed from that starting point when you eventually sell. If you contributed securities with a combined cost basis of $1 million and a fair market value of $5 million, you would receive ETF shares with a total cost basis of $1 million.

What does "in-kind" mean in this context?

An in-kind transfer means the securities themselves move from the investor's account to the ETF's custodian, without being converted to cash at any point in the process. Because there is no sale, there is no realized gain or loss. This is the mechanism that makes the non-recognition treatment of Section 351 possible.

Can my trust or partnership participate?

Revocable and irrevocable trusts, partnerships, and limited partnerships are generally eligible as transferors, subject to review of the specific entity's structure, beneficiaries, and ownership. Entities with C corporation partners or beneficiaries require additional analysis and should consult qualified tax counsel before proceeding.