Partner basis worksheet and the tax basis capital account

“Although the partnership provides an analysis of the partner’s capital account in item L of Schedule K-1, that information is based on the partnership’s books and records and can’t be used to figure the partner’s adjusted basis.” IRS, Partner's Instructions for Schedule K-1 (Form 1065) (2025)

What is partner basis and who has to track it?

Partner basis is the partner's adjusted basis in the partnership interest, and the partner, not the partnership, has to track it. Treas. Reg. 1.705-1(a)(1) requires a partner to determine adjusted basis when it is needed to figure tax, for example when a loss is claimed, an interest is sold or the interest is liquidated. The Partner's Instructions for Schedule K-1 (Form 1065) state that the partner is responsible for maintaining that record and that the K-1 doesn't report it.

Starting basis comes from IRC section 722 for a contribution (cash plus the adjusted basis of contributed property) or from section 742 for a purchased or inherited interest. Section 752(a) treats an increase in a partner's share of partnership liabilities as a contribution of money, and section 752(b) treats a decrease as a distribution of money. Section 705(a) then adjusts basis each year for the partner's distributive share of taxable income, tax-exempt income, losses and nondeductible expenses, and for distributions, never below zero.

Where does each K-1 item go on the partner basis worksheet?

The IRS Worksheet for Adjusting the Basis of a Partner's Interest in the Partnership, in the 2025 Partner's Instructions for Schedule K-1, has a fixed line for each Schedule K-1 (Form 1065) item. Positive amounts go on line 4 as increases, and losses and deductions go on line 15 in Part II, where they are limited to the basis that remains. The liability lines use item K1 at the beginning and end of the year, so a refinancing or a new loan changes basis even when nothing else on the K-1 does. Negative amounts never go on line 4. A box 1 loss goes on line 15a, column A, and last year's suspended loss of the same type goes on line 15a, column B.

Distributions are covered in more detail on the K-1 box 19 page, and the full box list is on the Schedule K-1 (Form 1065) page.

In what order does partner basis change?

The partner basis worksheet applies changes in a set order, so the same K-1 can produce a different allowed loss depending on the sequence. Basis first increases for contributions, liability increases and income. It then decreases for distributions and liability decreases, and any shortfall below zero is gain on line 11b. Nondeductible expenses and oil and gas depletion come off next, and losses and deductions come off last.

1. Add contributions, liability increases and income (lines 2 to 7)
2. Subtract distributions and liability decreases (lines 8 to 11)
3. Subtract nondeductible expenses and oil and gas depletion (lines 12 to 14)
4. Subtract losses and deductions, up to remaining basis (lines 15 to 18)

When losses exceed remaining basis, the Partner's Instructions allocate the allowed amount pro rata across each category of loss, and Treas. Reg. 1.704-1(d) carries the excess forward to the next year the partner has basis. Business interest expense is its own loss class. Some transactions and distributions require basis to be measured at the time of the event rather than in the worksheet's year-end order.

How is partner basis different from the K-1 item L capital account?

Partner basis and the tax basis capital account in K-1 item L use the same tax rules, but they measure different things and rarely match. According to the Partner's Instructions for Schedule K-1, the main reason is liabilities: outside basis includes the partner's share of partnership liabilities, and tax basis capital doesn't. Item L also leaves out section 743(b) adjustments, and the partnership may not know about partner-level adjustments that affect basis.

In a simple case with no 743(b) adjustment and no distribution in excess of basis, outside basis equals ending tax capital plus the share of liabilities plus any suspended losses. That identity is a useful tie-out when a client's basis schedule is missing. The Form 1065 page covers how the partnership builds item L.

What does a partner basis calculation look like?

For example, Sam starts 2025 with outside basis of $40,000: tax capital of $25,000 and a $15,000 share of partnership liabilities. His 2025 K-1 shows $2,000 of interest, $1,000 of tax-exempt income, $3,000 of nondeductible expenses, a $10,000 cash distribution and a $45,000 ordinary loss in box 1. His share of liabilities in item K1 rises to $21,000 by year end.

Sam's item L tells a different story. Beginning capital of $25,000, plus a current year net loss of $45,000 ($3,000 of income less $3,000 of nondeductible expenses and the $45,000 loss), less the $10,000 distribution, gives ending tax capital of negative $30,000. Adding the $21,000 liability share and the $9,000 suspended loss brings it back to outside basis of zero.

What do reviewers check on partner basis?

A reviewer checking partner basis confirms six items, each tied to the IRS worksheet or the Partner's Instructions for Schedule K-1. The first document to pull is last year's basis schedule, because line 1 beginning basis and every suspended loss in Part II, column B come from it.

The other documents are the current-year K-1 with every attached statement, any purchase or contribution records for interests acquired during the year, and the client's records of any partnership liabilities it assumed or that the partnership assumed from it. Where no prior basis schedule exists, the reviewer rebuilds it from the original contribution or purchase forward, year by year, using each year's K-1. Treas. Reg. 1.705-1(a)(1) requires basis in any year with a loss claimed, a sale or a liquidation.