What Is a 351 Exchange? Rules, Costs and the 2026 IRS Ruling

What a 351 Exchange Is and How It Works

A 351 exchange moves appreciated holdings into a newly launched ETF in return for shares of that fund, with no capital gain recognized at the transfer.

The mechanism comes from Section 351 of the tax code, which allows property to be contributed to a corporation without triggering gain when the contributors together control it afterward. An ETF is taxed as a corporation for this purpose, so a group of investors can seed a new fund with existing positions rather than cash. The fund issues shares, each contributor keeps their original cost basis, and the tax bill is deferred rather than paid.

The timeline is short. Members who have completed one describe receiving tradable ETF shares roughly a month after contributing, with the fund's holdings fully rebalanced four to six weeks after launch.

The structure has grown quickly. More than 100 ETFs have been seeded in kind under Section 351 since 2021, with over $20 billion in launch assets, according to a tracker cited by InvestmentNews.

Who Qualifies: The 25% and 50% Tests

You qualify for a 351 exchange only if the portfolio you contribute is already diversified: no more than 25% of its value in any one issuer, and no more than 50% in its five largest issuers.

The tests come from the definition of a diversified portfolio in Section 368, applied through the Section 351 regulations, which treat a transfer as not diversifying anyone's interest when each transferor contributes a diversified portfolio. Cash and government securities are excluded from the calculation. The tests apply to what each investor brings, not to the fund that results.

The first test is the one sponsors describe. The second catches people who assume they have cleared it: someone holding four large technology positions can keep each one under 25% and still have more than half the portfolio in the top five.

The working rule members use is dilution. A single stock needs roughly three dollars of other eligible holdings for every dollar of the position to stay at or under 25%. Someone holding a large single-stock position and little else cannot use a 351 exchange. Someone with a stale direct-indexed sleeve, several appreciated positions and one oversized holding generally can.

What the 2026 IRS Ruling Changed

On September 28, 2026, the IRS ruled that a 351 launch is a taxable exchange when, as part of a plan, the new ETF redeems an authorized participant's shares using the securities investors contributed.

Rev. Rul. 2026-20 addresses a specific pattern. Investors contribute a portfolio that passes the diversification tests but does not match what the fund intends to hold. An authorized participant, the market maker that creates and redeems ETF shares, contributes securities that do match, or cash to buy them. The fund then redeems the authorized participant's shares with the investors' original securities, often shortly after launch. The ruling treats each investor as having exchanged those securities with the authorized participant in a taxable transaction, and the result is the same with many investors.

The accompanying Notice 2026-62 sets the boundary. It expresses no view on a 351 launch seeded with assets consistent with the fund's investment thesis, which the fund intends and expects to keep absent a substantial change in circumstances. It also describes a partnership variation, in which investors too concentrated to pass the 25% test contribute to a partnership exchange fund that then takes part in a 351 launch, and says Treasury and the IRS are considering guidance to deny deferral on it.

Two features raise the stakes for anyone who has already contributed. The ruling is framed as an application of existing law, so it could reach contributions made before it was published. The notice adds that any further guidance could apply retroactively and that a transaction could be identified as a listed transaction, which carries its own disclosure requirements. Comments on the notice are due October 28, 2026.

What to Ask a Sponsor Before Contributing

After the ruling, the question that decides a 351 exchange is whether the fund intends to keep what you contribute.

The notice draws its line around the fund's plan rather than your portfolio alone, so the diligence moves to the sponsor. Four questions follow from the guidance:

• Does the fund's stated strategy hold the securities you are contributing, at roughly the weights you hold them?
• Does the sponsor expect to redeem creation units in kind shortly after launch, and with which securities?
• What tax opinion supports the launch, and does it address Rev. Rul. 2026-20?
• How will the transaction be reported if later guidance applies retroactively?

Put the same questions to your own tax counsel. This page describes the guidance; it is not tax advice, and the answer turns on facts in the fund's documents.

What a 351 Exchange Costs

Ongoing fees on 351 exchange ETFs have compressed to a level competitive with mainstream index funds, and the main added cost is the advisor who processes the contribution.

Members report ongoing expense ratios below ten basis points on some funds, with one sponsor having cut its fee since launch. Execution usually requires an advisor to process the contribution, and the reported cost of that step has been modest: one member describes a flat five basis points charged once, another a few hundred dollars in total.

The cost the ruling adds is harder to price. If a launch is recharacterized, the gain the exchange was meant to defer becomes taxable. Weigh a fee difference measured in basis points against that exposure, not only against another fund's fee.

351 Exchange vs Exchange Fund

A 351 exchange suits a holder whose portfolio is already diversified and who wants liquid shares within weeks; an exchange fund accepts a far more concentrated position in return for a lockup of seven years or more.

Source: Sources: 26 U.S.C. 351, 368(a)(2)(F), 704(c)(1)(B) and 737; Rev. Rul. 2026-20 and Notice 2026-62, September 28, 2026. Cost and minimum rows are member reports from a voluntary Long Angle discussion, not a survey.

The seven-year figure is a tax rule before it is a fund term. The tax code recognizes gain when contributed property returns to the contributing partner within seven years, which is why exchange fund lockups cluster where they do. Members who have read the terms closely describe withdrawal provisions that push the practical hold beyond seven years in some funds, so read the redemption terms rather than the summary.

An exchange fund also holds at least 20% of its assets in property other than stocks and securities, so the partnership is not treated as an investment company. That allocation is what lets a single concentrated stock in, and it is also the feature the notice's partnership variation relies on, which makes the fund's plan for its holdings worth asking about here too.

For a holder whose position is most of their net worth, the wider choice among exchange funds, staged sales, hedging and gifting is set out in our guide to concentrated stock positions.

What Members Report After Completing One

Members who have completed 351 exchanges describe the process as straightforward, with benchmark tracking closer than the differing composition would suggest. These accounts predate the September 2026 guidance.

Several have run more than one. Reported uses include contributing an exhausted direct-indexed portfolio, contributing a single large appreciated position alongside other holdings, and changing an allocation that had become impossible to adjust without a large tax bill. Tracking is described as very close once the post-launch rebalance completes, though the fund is not the index and holds discretion over what it owns.

The concerns members raise are manager risk, fund size and the strategy not being an index. On size, members who have diligenced it point to the creation and redemption mechanism, which lets authorized participants exchange fund shares for the underlying holdings, so tradable liquidity runs higher than daily volume suggests. One notes these funds are plausible candidates to be merged over time for scale.

On the exchange fund side, one member describes a hold of seven years and more that outperformed both its benchmark and the contributed position.

These are individual accounts from a voluntary discussion, not a survey. Long Angle's research on entrepreneur equity concentration covers how concentrated founders' portfolios tend to be.

When a 351 Exchange Is the Wrong Tool

A 351 exchange defers a gain rather than removing it, so a reader whose objective is different should look elsewhere first.

Members consistently raise four alternatives. Donating appreciated shares to a donor-advised fund, up to the amount of expected future giving, removes the gain on that portion; the vehicles are compared in our charitable giving strategies guide. Direct indexing generates harvested losses to offset gains from selling the position down, though members note the harvesting opportunity is finite and eventually exhausts. Holding until death passes the position with a stepped-up basis. And selling in tranches, accepting the tax, is the option most often underrated in the discussion.

One caution recurs: option-based hedging can convert what would have been long-term capital gain into ordinary income, which changes the arithmetic materially. Sequencing these choices before a sale is covered in our guide to liquidity event planning, and the errors that recur are set out in common tax mistakes.

The point members return to is that a concentrated position is a risk decision before it is a tax decision. Several describe regret after selling into a continued run, and the advice that repeats is to settle risk tolerance first and optimize the tax treatment second.