Form 8990: Understanding the business interest expense limitation

Your business carries debt. You pay interest on acquisition loans, operating lines of credit, equipment financing, or real estate mortgages. For decades, that interest expense reduced your taxable income dollar for dollar. Interest was just another deductible business expense.

Then the Tax Cuts and Jobs Act changed the rules. Section 163(j) now limits how much business interest you can deduct each year. For businesses that exceed the gross receipts threshold, the interest expense deduction limit caps deductible interest at 30% of adjusted taxable income. Pay more interest than that, and the excess cannot be deducted until future years.

Form 8990 calculates this business interest limitation. Understanding the Form 8990 instructions determines whether you are subject to the limit, how much interest you can deduct, and how to track disallowed interest for future use.

The limitation applies to businesses exceeding the gross receipts threshold

Not every business is subject to Section 163(j). The rules include a small business exemption that protects most professional service firms from the limitation.

1. The threshold is $30 million in average gross receipts. For tax years beginning in 2024, businesses with average annual gross receipts of $30 million or less over the prior three years are exempt from the limitation. This threshold is adjusted annually for inflation.

Average gross receipts means you add up gross receipts for the three preceding tax years and divide by three. A business with gross receipts of $25 million, $28 million, and $32 million over the past three years has an average gross receipts of $28.3 million and remains exempt.

2. Most professional service firms qualify for the exemption. A consulting firm, law practice, accounting firm, or similar professional services business with revenues under $30 million is not subject to Section 163(j). Interest expense remains fully deductible without limitation.

This exemption is the most important point for many readers. If your business is below the threshold, the business interest limitation does not apply, and you do not need to complete Form 8990 unless you are part of a larger group or have other special circumstances.

3. Certain businesses are exempt regardless of size. Real property trades or businesses that make an irrevocable election are exempt from the limitation. Farming businesses can opt out. Certain regulated utilities are also exempt. These elections have trade-offs, including the requirement to use the alternative depreciation system for real property.

4. Tax shelters are never exempt. Even if a business meets the small business exception, it remains subject to Section 163(j) if it is a tax shelter as defined in the code.

SectionSection 163(j) caps interest at 30% of ATI

For businesses subject to the limitation, the calculation determines how much interest expense is deductible in the current year.

1. Start with the ATI calculation. Adjusted taxable income begins with your taxable income and adds back business interest expense, net operating loss deductions, and certain other items. For tax years beginning before 2022, depreciation, amortization, and depletion were also added back, but this add-back has expired for most taxpayers.

ATI represents the earnings base against which interest deductions are measured. It approximates cash flow available to service debt before the interest itself is deducted.

2. Calculate the limitation amount. Multiply ATI by 30%. This is your section 163(j) limitation. If your business has an ATI of $1 million, the limitation is $300,000.

3. Add business interest income and floor plan financing interest. The limitation amount increases by any business interest income you received and any floor plan financing interest (relevant primarily for vehicle dealers). If you have $1 million ATI, $50,000 in interest income, and no floor plan financing, your total limitation is $350,000.

4. Compare to the actual business interest expense. If your business interest expense is less than the limitation, all interest is deductible. If business interest expense exceeds the limitation, only the limitation amount is deductible. The excess is disallowed for the current year.

A business with $400,000 in interest expense and a $350,000 limitation deducts $350,000 and has $50,000 of disallowed interest.

Interest carryforward preserves future deductions

Disallowed business interest is not permanently lost. It carries forward to future years, where it can be deducted subject to that year's limitation.

1. The carryforward is indefinite. Unlike some tax attributes that expire, disallowed business interest carries forward indefinitely until used. There is no time limit on claiming the carryforward deduction.

2. Carryforwards are used after current-year interest. In a future year, you first apply your current-year interest expense against that year's limitation. If the limitation capacity remains, you then deduct carryforward interest from prior years, oldest first.

A business with $200,000 of current-year interest, $100,000 of carryforward interest, and a $350,000 limitation deducts all $300,000. The excess $50,000 of limitation capacity does not carry forward; use it or lose it.

3. Partnerships and S corporations have special rules. For pass-through entities, the limitation applies at the entity level, but excess business interest expense may be allocated to partners or shareholders as excess business interest expense (EBIE). The partners and shareholders track EBIE separately and can deduct it only when they have excess taxable income from the same partnership or S corporation.

This pass-through treatment adds complexity. Partners may have carryforward interest at the entity level and EBIE at the individual level, each with different utilization rules.

Form 8990 reports the calculation and tracks carryforwards

The Form 8990 instructions walk through calculating your limitation, determining allowable deductions, and tracking carryforwards.

1. Part I determines whether you are subject to the limitation. Answer questions about your gross receipts, whether you are a tax shelter, and whether you have made any elections. If you qualify for the small business exemption and have no other characteristics requiring the form, you may not need to complete the remainder.

2. Part II calculates the limitation. Report your ATI calculation, apply the 30% limitation, add business interest income and floor plan financing interest, and determine your total limitation amount.

3. Part III applies the limitation to your interest expense. Report your business interest expense, compare it to your limitation, and calculate the allowable deduction and any disallowed amount.

4. Part IV tracks carryforwards. Report disallowed interest from prior years brought into the current year, interest utilized in the current year, and disallowed interest carried forward to the next year.

5. Partnerships and S corporations complete additional sections. Pass-through entities report information that flows to partners and shareholders, including excess business interest expense allocations.

Planning around the interest limitation

Understanding Section 163(j) creates opportunities to manage its impact.

1. Monitor your gross receipts. If your business is approaching the $30 million threshold, track your three-year average carefully. Crossing the threshold subjects you to the limitation and requires you to file Form 8990. Staying below preserves the small business exemption.

2. Consider the timing of interest payments. If you expect higher ATI in future years, disallowed interest carryforwards may be more valuable later. Conversely, if ATI is currently high, maximizing current-year interest expense captures the deduction when the limitation is most favorable.

3. Evaluate entity structure. The pass-through rules for partnerships and S corporations add complexity and may limit the utilization of interest at the individual level. C corporations do not pass through EBIE and may handle interest limitations more simply in some situations.

4. Real estate businesses should evaluate the election. The election to be treated as a real property trade or business exempts you from Section 163(j) but requires using the alternative depreciation system for real property. The trade-off between unlimited interest deductions and slower depreciation depends on your specific numbers.

The limitation matters when interest expense is significant

For most professional service firms under the gross receipts threshold, Section 163(j) has no practical impact. Interest expense remains fully deductible, and Form 8990 is not required.

For larger businesses or those with substantial debt, the limitation can materially affect taxable income. Understanding the section 163(j) calculation, filing Form 8990 correctly, and tracking carryforwards ensures you capture the maximum allowable deduction each year while preserving disallowed interest for future use.

The rules are technical, but the concept is straightforward. Your interest deduction is capped at 30% of earnings. Anything above that limit is put off until future years. Form 8990 documents the math and tracks what is waiting.