U.S. · Tax forms
Form 8990 line 6, tentative taxable income.
The starting point for adjusted taxable income under the section 163(j) interest limit.
Line 6 (“Tentative taxable income”) is your taxable income computed as though all of the business interest expense is otherwise allowable. It is the starting point for adjusted taxable income (ATI) on line 22, after the additions on lines 7 through 16 and the reductions on lines 17 through 21.
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Where line 6 fits in ATI
| Item | Meaning | What the IRS says |
|---|---|---|
| Line 6 | Tentative taxable income | Computed as though all of the business interest expense is otherwise allowable business interest expense. |
| Other limits first | Apply before line 6 | Consider all other applicable limitations such as sections 163(f), 267, basis (sections 704 and 1366), at-risk (section 465), passive activity loss (section 469), and excess business loss (section 461(l)) limitations prior to inputting the amount. |
| Partnership | Generally | Form 1065, Analysis of Net Income (Loss), line 1, Net income (loss), less guaranteed payments, Schedule K, line 4c. |
| S corporation | Generally | Form 1120-S, Schedule K, line 18, Income/loss reconciliation. |
| Pass-through items | Include both kinds | The tentative taxable income of a partnership or S corporation shall include both separately and non-separately stated items. |
| Lines 7 to 16 | Additions | Add back to tentative taxable income certain adjustments to arrive at ATI. |
| Lines 17 to 21 | Reductions | Subtract from tentative taxable income certain adjustments to arrive at ATI. |
| Line 22 | Adjusted taxable income | Combine lines 6, 16, and 21. If line 22 is zero or less, enter zero (CFC group members follow separate instructions). |
What “tentative” means here
Line 6 is not final taxable income. It is the taxable income you would have if no business interest were disallowed by section 163(j). That is why line 8 adds business interest expense back: the interest has already reduced line 6, and ATI is measured before it.
Limits to apply before line 6
The instructions list other limitations to consider before inputting the amount, among them sections 163(f) and 267 and the basis, at-risk, passive activity loss and excess business loss limitations. The 163(j) computation sits on top of those, not in place of them.
Partnerships and S corporations
For a partnership, line 6 generally comes from Form 1065 Analysis of Net Income (Loss) line 1 less guaranteed payments and Schedule K line 4c, with the effects of section 743(b) basis adjustments removed. For an S corporation, it generally comes from Form 1120-S Schedule K line 18. Adjustments from section 734(b) and 743(b) are entered on line 13 (or line 20).
Worked example
Made-up numbers. A business has $500,000 of income before interest and $100,000 of business interest expense (not from a pass-through entity). Its taxable income with all interest deducted is $400,000, which goes on line 6. Line 8 adds the $100,000 back, and with no other adjustments the ATI on line 22 is $500,000.
More line pages in this set
Related lines: Form 8990 Line 11, Form 8990 Line 19, Form 8990 Line 30.
Sources
- Instructions for Form 8990 (12/2025): the line-by-line instructions on this page. Page last reviewed or updated April 30, 2026. Read November 2, 2026.
- Form 8990 (Limitation on Business Interest Expense Under Section 163(j)): the printed line wording and arithmetic on the form. Read November 2, 2026.
Instructions for Form 8990, December 2025 revision. The line labels were read from the Form 8990 (Rev. December 2025) PDF the IRS had posted on the date read. Line numbers can shift between years, so check them against the form for your tax year. Examples marked made-up use invented figures; the others reproduce the IRS’s own examples.
Frequently asked questions
What goes on Form 8990 line 6?
Tentative taxable income, computed as though all of the business interest expense is otherwise allowable.
Is line 6 the same as taxable income?
Not exactly. It is taxable income figured as if no business interest were limited by section 163(j), after considering other limitations such as at-risk and passive loss rules.
What does a partnership use for line 6?
Generally Form 1065 Analysis of Net Income (Loss) line 1 less guaranteed payments and Schedule K line 4c, with section 743(b) effects removed.
What does an S corporation use?
Generally Form 1120-S, Schedule K, line 18, Income/loss reconciliation.
What comes after line 6?
Additions on lines 7 through 16, reductions on lines 17 through 21, and ATI on line 22 (lines 6, 16 and 21 combined).
Not tax advice
This page summarizes IRS instructions, mostly written for the people who prepare the form, and is not tax, legal or financial advice. A CPA or an enrolled agent can confirm what a line means for your return. Everything runs in your browser; nothing you enter is sent anywhere.