Mandatory Basis Adjustment for Substantial Built-In Loss

A partnership must reduce the incoming partner’s share of its asset basis whenever a partnership interest changes hands and the partnership’s built-in losses cross a $250,000 threshold. This substantial built-in loss mandatory basis adjustment, imposed by Internal Revenue Code Section 743(b), is not something the partnership elects into. Once either of two loss tests is failed, the adjustment happens by operation of law, and the partnership has to compute it, allocate it across assets, and report it on the transferee’s Schedule K-1.

The Two $250,000 Tests

A partnership has a substantial built-in loss if it fails either of two independent tests. Failing one is enough.

The first test looks at the partnership as a whole. If the total adjusted basis of all partnership property exceeds the total fair market value of that property by more than $250,000, the loss is substantial.¹ Because this is a net calculation, gains on appreciated property offset losses on depreciated property. A partnership holding one building worth $2 million less than its tax basis alongside land that has appreciated by $1.8 million has a net built-in loss of only $200,000 and passes.

The second test zeroes in on the transferee. Even if the partnership as a whole clears the first test, the adjustment is still mandatory if the incoming partner would be allocated a loss exceeding $250,000 in a hypothetical immediate liquidation where every asset sold for its fair market value.¹ The Tax Cuts and Jobs Act added this transferee-level test, which catches situations where a specific partner’s capital account or debt allocation concentrates losses on them even though aggregate numbers look fine.² Before 2018, only the entity-wide test mattered.

What Triggers the Adjustment

Two events can trigger the mandatory adjustment: a sale or exchange of a partnership interest, or the death of a partner.¹ A sale or exchange covers any negotiated buyout, whether a new investor purchases a stake from a departing partner or two partners swap interests. Death transfers the interest to an heir or estate and typically gives it a stepped-up or stepped-down basis under Section 1014, which itself creates a gap between the new outside basis and the partnership’s inside basis.

The key point: no Section 754 election is required. Ordinarily a partnership can choose whether to file that election and begin adjusting its property basis when interests change hands.³ Once either substantial built-in loss test is met, there is no choice. The adjustment applies whether the partnership has ever filed a Section 754 election or not.

Calculating the Adjustment

The adjustment equals the difference between the transferee’s outside basis and their proportionate share of the partnership’s inside basis. The outside basis is straightforward. For a purchase, it is the amount the buyer paid for the interest plus their share of partnership liabilities. For an inherited interest, it is the fair market value at the date of death (or alternate valuation date) plus the heir’s share of partnership liabilities.

The inside basis takes more work. It represents the partnership’s total tax basis in all assets, allocated to the specific partner based on their share of capital and profits. When a substantial built-in loss exists, the transferee’s share of inside basis will exceed their outside basis, producing a negative adjustment. That negative number is the amount by which the partnership must reduce asset basis for purposes of computing the transferee’s share of income, deduction, gain, and loss.

Getting the number right depends on reliable fair market values for every partnership asset at the time of the transfer. Real estate, equipment, and intangibles like goodwill often need formal appraisals. The IRS computes built-in gain or loss on an asset-by-asset basis, so aggregate estimates will not hold up.² Weak valuation is where partnerships create problems for themselves, because the IRS can challenge both the threshold determination and the allocation if the numbers are poorly supported.

Allocating the Adjustment Across Assets

Once the total adjustment is known, Section 755 requires the partnership to divide it between two buckets of property.⁴ The first bucket covers capital assets and Section 1231 property: real estate, equipment held for more than a year, and investment holdings. The second covers ordinary income property, meaning inventory, accounts receivable, and any other assets that would produce ordinary income on sale.⁵

Within each bucket, the adjustment spreads across individual assets in proportion to the difference between each asset’s fair market value and its tax basis. A negative adjustment reduces the basis of assets carrying built-in losses and leaves appreciated assets alone. The regulation treats unrealized receivables as separate ordinary income assets for allocation purposes, which matters for partnerships with significant unbilled work.⁵ One hard limit: no asset’s basis can be reduced below zero.

How It Affects the Incoming Partner’s Taxes

The basis adjustment belongs to the transferee alone. The partnership’s books stay the same for everyone else, and it continues computing income, deductions, and gains the same way it always has for other partners. For the transferee, the partnership maintains a separate, adjusted basis for each affected asset.⁶

A downward adjustment has two practical consequences for that partner. Depreciation and amortization from affected assets shrinks, because a negative basis adjustment allocated to depreciable property directly reduces the transferee’s annual deduction. And when the partnership eventually sells an asset carrying a negative adjustment, the transferee recognizes more gain (or less loss) than they otherwise would. The transferee’s gain equals their regular share of the partnership’s gain on the sale plus the amount of the negative basis adjustment for that asset.⁶

The net effect is that the new partner cannot use pre-existing losses to shelter their own income. Their tax results match what they actually paid for or inherited, not value declines that economically belonged to a prior owner.

Partnerships That Are Carved Out

Two categories of partnerships are exempt from the substantial built-in loss rules entirely, even if they would otherwise fail the $250,000 tests.

Electing Investment Partnerships

A partnership that qualifies as an electing investment partnership is not treated as having a substantial built-in loss for any transfer while the election is in effect.¹ The trade-off matters: losses that would otherwise flow to the transferee are deferred, and the transferee can only claim losses on asset sales to the extent they exceed any loss the prior owner already recognized when selling the partnership interest.

Qualifying is deliberately restrictive. The partnership must satisfy all of these conditions:

It has never operated a trade or business, and substantially all assets are held for investment.
At least 95 percent of contributed assets were cash, and no contributed asset had a basis above its fair market value at contribution.
All interests were issued through a private offering within 24 months of the first capital contribution.
The partnership agreement limits each partner’s ability to redeem their interest and caps the partnership’s term at 15 years.
The partnership would qualify as an investment company under the Investment Company Act of 1940 but for certain exemptions.

The election is irrevocable without IRS consent.¹

Securitization Partnerships

A securitization partnership is also exempt. To qualify, its sole business activity must be issuing securities backed by a defined pool of receivables or other financial assets that convert into cash over a fixed period.¹

Reporting on Form 1065 and Penalties

The partnership must attach a statement to its Form 1065 for the tax year the transfer occurred. The statement identifies the transferee partner (including taxpayer identification number), shows the computation of the basis adjustment, and specifies which partnership assets received the adjustment and in what amounts. The partnership then adjusts the transferee’s share of all income, deduction, gain, and loss items to reflect the basis adjustment and reports those figures on the transferee’s Schedule K-1.⁷

Getting this wrong is expensive. A partnership that fails to file a complete and timely Form 1065 faces a penalty of $255 per partner per month (or partial month) the return is late or incomplete, for up to 12 months.⁸ For a 10-partner entity, that adds up to $30,600 over a full year. The penalty applies per partner who was a member at any point during the tax year, not only the transferee, so larger partnerships face outsized exposure. Filing on time with accurate basis adjustment disclosures is the most straightforward way to avoid it.

1
Office of the Law Revision Counsel. 26 USC 743 – Special Rules Where Section 754 Election or Substantial Built-In Loss
2
Internal Revenue Service. Questions and Answers About the Substantial Built-In Loss Changes Under IRC Section 743
3
Office of the Law Revision Counsel. 26 USC 754 – Manner of Electing Optional Adjustment to Basis of Partnership Property
4
GovInfo. 26 USC 755 – Rules for Allocation of Basis
5
eCFR. 26 CFR 1.755-1 – Rules for Allocation of Basis
6
eCFR. 26 CFR 1.743-1 – Optional Adjustment to Basis of Partnership Property
7
Internal Revenue Service. Instructions for Form 1065 (2025)
8
Internal Revenue Service. Failure to File Penalty