What do the box 20 codes on a partnership Schedule K-1 mean?

Common box 20 codes

All descriptions below are from the Partner's Instructions for Schedule K-1 (Form 1065) for 2025.

Code	What it is	What the partner does with it
A	Investment income	Form 4952, Part II, line 4a
B	Investment expenses	Form 4952, Part II, line 5
N	Business interest expense	Information only. It is already deducted elsewhere on the K-1 and is used for the IRC §704(d) basis limit
Z	Section 199A information	Form 8995 or Form 8995-A for the QBI deduction
AA	Section 704(c) information	Shows income or deduction allocated under §704(c). Already included in other K-1 items
AB	Section 751 gain (loss)	Partner's share of gain or loss on selling the partnership interest that is taxed at ordinary rates
AC	Collectibles gain, IRC §1(h)(5)	Gain on selling the interest taxed at the collectibles rate
AD	Unrecaptured section 1250 gain, IRC §1(h)(6)	Gain on selling the interest taxed at the unrecaptured §1250 rate
AE	Excess taxable income	Form 8990, Schedule A, line 43, column (f), if the partner must file Form 8990
AF	Excess business interest income	Form 8990, Schedule A, line 43, column (g), if required
AG	Gross receipts for section 448(c)	Partner's share of gross receipts, for the §163(j) small business test
AH	Noncash charitable contributions	Limited to the partner's outside basis (IRC §704(d)(3))
AJ	Excess business loss limitation	Statement used with Form 461 (IRC §461(l))
AM	Section 1061 information	Capital gain figures for an applicable partnership interest (carried interest). See Pub. 541

Code Z in more detail

The QBI deduction is figured at the partner level (IRC §199A(f)(1)(A)), so the partnership reports the pieces in code Z, usually on an attached statement. For 2025, the instructions say to use Form 8995 if all three apply: the partner has QBI, section 199A dividends or PTP income; taxable income before the QBI deduction is $197,300 or less ($394,600 married filing jointly); and the partner isn't a patron of a specified agricultural or horticultural cooperative. Otherwise use Form 8995-A.

Codes AB, AC and AD

These only appear when a partner sold a partnership interest. The instructions note the same information is reported by the partnership on Part IV of Form 8308. The partnership may also report collectibles gain and unrecaptured §1250 gain in boxes 9b and 9c.