The Section 163(j) business interest expense limitation is one of the most significant tax provisions affecting businesses that carry debt. Introduced by the Tax Cuts and Jobs Act (TCJA) of 2017, this rule caps the amount of business interest expense a taxpayer can deduct in a given tax year. For companies with substantial borrowing, whether for capital investments, acquisitions, or operations, understanding how this limitation works is essential to accurate tax planning and compliance.
Before the TCJA, most businesses could deduct interest expense without meaningful restriction. Section 163(j) changed that by imposing a formula-based ceiling on deductible business interest. The rule applies broadly across entity types, including C corporations, S corporations, and partnerships, though certain industries and smaller businesses may qualify for exceptions. This article answers the core question every borrower asks: how much of my business interest can I actually deduct, and what happens to the rest?
How the Section 163(j) limitation works
Section 163(j) limits a taxpayer’s deductible business interest expense to the sum of three components: business interest income, 30% of adjusted taxable income (ATI), and floor plan financing interest. In practice, the 30% of ATI threshold is the operative limit for most taxpayers, because business interest income and floor plan financing are zero or negligible for the majority of businesses.
Adjusted taxable income is not the same as taxable income. ATI starts with taxable income and then adds back certain items, including business interest expense, net operating loss deductions, and the Section 199A qualified business income deduction. The treatment of depreciation, amortization, and depletion has changed over time. For tax years beginning before January 1, 2022, those items were added back, making ATI closer to EBITDA. For tax years beginning in 2022, 2023, and 2024, the addback was no longer allowed, shifting the calculation to an EBIT-based measure that reduced the amount of interest many capital-intensive businesses could deduct. The One Big Beautiful Bill Act (OBBBA) then restored the depreciation, amortization, and depletion addback, and made it permanent, for tax years beginning after December 31, 2024. As a result, the current EBITDA-based ATI calculation generally allows businesses with significant capital assets to deduct more interest than they could during the 2022 through 2024 window.
Any business interest expense that exceeds the Section 163(j) limitation in a given year is not lost. Instead, the disallowed interest is carried forward indefinitely and can be deducted in future tax years when the taxpayer has sufficient ATI capacity. For partnerships, the carryforward rules operate differently, because excess business interest expense is allocated to partners and tracked at the partner level rather than the partnership level. The IRS provides the governing rules and worksheets in the Form 8990 instructions.
Who is subject to the interest expense limitation
Nearly every business taxpayer with net business interest expense is potentially subject to the Section 163(j) limitation. The rule applies to sole proprietorships, C corporations, S corporations, partnerships, and certain tax-exempt organizations that conduct unrelated trade or business activities. The limitation is calculated at the entity level for corporations and at the partnership level for partnerships, with specific allocation rules flowing excess amounts to partners.
There are, however, important categories of taxpayers that are exempt. The most significant is the small business exception, which exempts taxpayers (other than tax shelters) that meet the gross receipts test under Section 448(c). The statutory base figure is $25 million in average annual gross receipts for the three prior tax years, and that amount is indexed for inflation. The inflation-adjusted threshold was $30 million for tax years beginning in 2024 and $31 million for tax years beginning in 2025. This test is applied on an aggregated basis, meaning related entities under common control must combine their gross receipts when testing against the limit. Small businesses that meet the test can deduct all of their interest expense without regard to Section 163(j).
Certain industries also benefit from elective exclusions. Real property trades or businesses and farming businesses can elect out of the Section 163(j) limitation entirely. Making this election comes with a trade-off, because taxpayers who elect out must use the alternative depreciation system (ADS) for certain property, which typically results in longer recovery periods and straight-line depreciation rather than accelerated methods like MACRS. Borrowers in the real estate sector frequently weigh this election as part of broader entity and depreciation planning.
Calculating adjusted taxable income under Section 163(j)
The ATI calculation is the core of the Section 163(j) limitation, and getting it right is critical. For tax years beginning after December 31, 2024, the computation starts with taxable income and makes the following adjustments:
- Add back business interest expense
- Add back any net operating loss (NOL) deduction
- Add back the Section 199A qualified business income deduction
- Add back depreciation, amortization, and depletion (restored permanently by OBBBA for tax years beginning after December 31, 2024)
- Subtract business interest income
The depreciation, amortization, and depletion addback is the figure that has moved the most. It was available for tax years beginning before 2022, disallowed for tax years beginning in 2022 through 2024, and then restored on a permanent basis by OBBBA for tax years beginning after December 31, 2024. During the 2022 through 2024 window, businesses with significant capital assets, including manufacturers, real estate developers, oil and gas companies, and utilities, saw their ATI drop substantially, which reduced deductible interest and inflated carryforward balances. The return to an EBITDA-based measure reverses that effect for current and future years.
Consider an example. A manufacturing company has $10 million in taxable income, $4 million in depreciation, and $5 million in business interest expense. Under the EBIT approach that applied for 2022 through 2024, ATI was $15 million ($10M + $5M interest, with no depreciation addback), and the limit was $4.5 million (30% of $15M), leaving $500,000 of disallowed interest to carry forward. Under the EBITDA approach that applies for tax years beginning after December 31, 2024, ATI is $19 million ($10M + $4M depreciation + $5M interest), and the limit rises to $5.7 million (30% of $19M), enough to fully deduct the interest. Capital-intensive operators such as those in manufacturing feel this shift most acutely.
The small business exception to Section 163(j)
The small business exception under Section 163(j) provides a complete exemption from the interest expense limitation for taxpayers meeting the gross receipts test. A taxpayer qualifies if its average annual gross receipts for the three preceding tax years do not exceed the inflation-adjusted threshold. The statutory base is $25 million, and indexing raised it to $30 million for tax years beginning in 2024 and $31 million for tax years beginning in 2025, with further adjustments expected in later years.
The gross receipts test applies on an aggregated basis under Section 448(c). All entities treated as a single employer under Sections 52(a) and (b) or Section 414(m) and (o) must combine their gross receipts. This aggregation requirement prevents businesses from splitting operations across multiple entities to remain below the threshold. The statutory framework appears in 26 U.S.C. 163(j) for taxpayers who want to confirm the precise language.
Taxpayers who meet the small business exception do not need to file Form 8990 solely for Section 163(j) purposes, though they may still have filing obligations if they are part of a group where other members are subject to the limitation. For qualifying small businesses, the exception significantly simplifies compliance by eliminating the need to track ATI, carryforward amounts, and partner-level allocations.
Filing requirements: Form 8990 and business interest expense
Taxpayers subject to the Section 163(j) limitation must file Form 8990, _Limitation on Business Interest Expense Under Section 163(j)_, with their federal income tax return. This form calculates the taxpayer’s allowable business interest expense deduction and tracks any disallowed interest carried forward from prior years.
Form 8990 requires detailed inputs, including the taxpayer’s business interest expense, business interest income, floor plan financing interest, and ATI. Schedule A of Form 8990 provides additional detail for taxpayers who are partners in partnerships or shareholders in S corporations, because excess business interest expense from these entities is tracked separately at the owner level.
Partnerships have unique reporting obligations. When a partnership’s business interest expense exceeds the Section 163(j) limitation, the excess is allocated to each partner as excess business interest expense (EBIE). Partners must track their EBIE and can only deduct it in future years when they receive excess taxable income or excess business interest income from that same partnership. This partner-level tracking adds a layer of complexity that makes Form 8990 particularly important for taxpayers with partnership investments.
The IRS has updated Form 8990 and its instructions multiple times since Section 163(j) was expanded by the TCJA. Taxpayers should use the version of the form that corresponds to their tax year and review the instructions carefully, because the calculation mechanics, particularly around the depreciation addback transition, vary by year. Coordinating these filings with experienced tax advisory services reduces the risk of misstated carryforwards.
Planning strategies for managing the interest expense limitation
Tax planning around Section 163(j) involves evaluating several variables that affect ATI and, by extension, deductible interest. Common strategies include the following approaches.
Timing of deductions. Because ATI starts with taxable income, accelerating revenue recognition or deferring other deductions can increase ATI and allow more interest to be deducted in the current year. Conversely, taxpayers with large carryforwards may prefer to time income and deductions to maximize the use of those carryforwards.
Entity structure. The choice between operating as a C corporation, S corporation, or partnership affects how the Section 163(j) limitation is applied and how carryforwards are tracked. For partnerships, the partner-level tracking of excess business interest expense creates both planning opportunities and compliance burdens.
Electing out. Real property trades or businesses and farming businesses should evaluate whether electing out of Section 163(j) produces a net tax benefit after accounting for the required switch to ADS depreciation. In many cases, the immediate benefit of fully deducting interest outweighs the cost of slower depreciation recovery.
Debt restructuring. Refinancing or restructuring debt to reduce interest expense below the Section 163(j) threshold can eliminate disallowed interest entirely. Businesses with borderline interest levels should model the impact of rate changes, principal payments, and refinancing on their Section 163(j) position.
Working with a tax advisor who understands the interplay between Section 163(j), depreciation methods, and entity-level rules is critical, especially for businesses in capital-intensive industries where the limitation has the greatest impact. The broader range of accounting services that supports modeling, compliance, and forecasting can help borrowers quantify the cost of disallowed interest before it appears on a return.
Frequently Asked Questions
What is Section 163(j) and why does it matter?
Section 163(j) is a provision in the Internal Revenue Code that limits the amount of business interest expense a taxpayer can deduct. It matters because businesses with significant debt may be unable to deduct all of their interest in the year it is paid or accrued, which increases their taxable income and current-year tax liability.
How is the interest expense limitation calculated?
The deductible amount equals the sum of business interest income, 30% of adjusted taxable income (ATI), and floor plan financing interest. For most businesses, the operative cap is 30% of ATI. Any interest exceeding this limit is carried forward indefinitely.
What qualifies a business for the small business exception?
A business qualifies for the small business exception if its average annual gross receipts for the three prior tax years do not exceed the inflation-adjusted threshold under Section 448(c). The statutory base is $25 million, indexed to $30 million for 2024 and $31 million for 2025. Related entities under common control must aggregate their gross receipts when applying this test.
How has the ATI calculation changed over time?
For tax years beginning in 2022 through 2024, taxpayers could not add back depreciation, amortization, and depletion when calculating ATI, which shifted ATI to an EBIT-based measure and reduced the deduction limit for capital-intensive businesses. The One Big Beautiful Bill Act restored those addbacks on a permanent basis for tax years beginning after December 31, 2024, returning ATI to the more favorable EBITDA-based measure.
Who needs to file Form 8990?
Any taxpayer subject to the Section 163(j) limitation must file Form 8990 with their federal income tax return. Partnerships allocating excess business interest expense to partners must also complete Schedule A. Small businesses that meet the gross receipts exception are generally not required to file Form 8990 solely for Section 163(j) purposes.
What happens to disallowed business interest expense?
Disallowed interest is carried forward indefinitely and can be deducted in future tax years when the taxpayer’s ATI capacity allows. For partnerships, disallowed interest is allocated to partners as excess business interest expense and tracked at the partner level, not the partnership level.
