Partnership tax deductions fall into two buckets: costs the partnership writes off on Form 1065 before splitting income, and deductions each partner claims personally on their own return. The partnership itself pays no federal income tax; it reports income and expenses on Form 1065 and passes each partner’s share through on Schedule K-1.1Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income Between those two levels sit three separate limits that can stop an allocated loss from ever reducing a partner’s tax bill, so knowing what qualifies is only half the work.
Operating Costs Deducted on Form 1065
Standard operating expenses come off the partnership’s income before anything is allocated to partners. They must be “ordinary and necessary” for the business, the same standard that governs any trade or business.2Office of the Law Revision Counsel. 26 U.S. Code 162 – Trade or Business Expenses Rent, utilities, business insurance, office supplies, repairs, advertising, and wages paid to non-partner W-2 employees all qualify.
Vehicle costs can be tracked two ways. The partnership either records actual expenses or uses the IRS standard mileage rate, which is 72.5 cents per business mile for 2026.3Internal Revenue Service. IRS Sets Business Standard Mileage Rate If the partnership owns the vehicle, the standard rate has to be chosen in the first year of business use. A leased vehicle placed on the standard rate stays on that method for the entire lease.
Business interest is deductible, but larger partnerships face a cap. When average annual gross receipts exceed the threshold, the deduction generally cannot exceed business interest income plus 30% of adjusted taxable income.4Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense Smaller partnerships that fall below the gross receipts test are exempt entirely, and any disallowed interest carries forward.
Once operating costs are netted against revenue, the partnership’s ordinary business income or loss is split among partners according to the partnership agreement and reported on each Schedule K-1.
How Partners Get Paid and What That Deducts
Partners are not employees. The IRS treats them as self-employed, and a partnership cannot issue a W-2 to someone acting in their capacity as a partner.5Internal Revenue Service. Partnerships That single rule drives most of what follows.
Guaranteed Payments
A guaranteed payment is a fixed amount paid to a partner for services or the use of capital, whether or not the business turns a profit. Consider a managing partner drawing $10,000 a month. The partnership deducts that amount as an operating expense on Form 1065, which lowers the ordinary income allocated to everyone.
The receiving partner reports the payment as ordinary income and pays self-employment tax on it, covering both Social Security and Medicare. Guaranteed payments appear in Box 4 of Schedule K-1 and are taxable even if the cash never actually leaves the partnership account.
Health Insurance and Half of Self-Employment Tax
Partners generally do not get the tax-free fringe benefits available to regular employees. When the partnership pays a partner’s health insurance premium, the IRS treats that payment as a guaranteed payment. The partner includes the premium in taxable income, then claims the self-employed health insurance deduction on Form 1040, which offsets the income tax. The partnership deducts the premium as an operating expense.
Every partner also gets an above-the-line deduction for half of the self-employment tax paid. It does not reduce the self-employment tax itself, but it lowers adjusted gross income, which can matter for other income-based thresholds. It applies whether you itemize or not.
Unreimbursed Partner Expenses and Home Office
When a partner pays business costs personally, treatment depends entirely on the partnership agreement. If the agreement requires the partner to bear those costs without reimbursement, the expenses reduce the partner’s distributive share and are reported on Schedule E. They cannot be claimed as itemized deductions under current law.
If reimbursement was available and the partner simply did not request it, the expense is generally lost to everyone. The cleaner path is an expense report: the partnership reimburses the partner and deducts the amount, and the reimbursement is not taxable income to the partner.
Home office costs follow the same logic. A partner using part of their home regularly and exclusively for partnership business can deduct those costs on Schedule E only if the partnership agreement expects the partner to maintain a home office at their own expense. The space also has to qualify as the partner’s principal place of business.
Writing Off Capital Purchases
Long-term assets cannot be deducted in full under standard rules. The cost is recovered over time through depreciation, amortization, or an accelerated election, all calculated at the partnership level and allocated on Schedule K-1.
Depreciation and Bonus Depreciation
Tangible property with a useful life beyond one year is depreciated under MACRS. Nonresidential buildings use straight-line depreciation over 39 years, residential rental over 27.5. Equipment, vehicles, and furniture use shorter schedules of five or seven years, with the deduction front-loaded.
Bonus depreciation lets the partnership write off 100% of the cost of qualifying property in the year it is placed in service. The One Big Beautiful Bill Act permanently reinstated this full first-year write-off for eligible assets acquired after January 19, 2025. The partnership claims the deduction on Form 4562, and the resulting amount flows to each partner’s K-1.
Section 179 Expensing
Section 179 is another path to an immediate deduction, covering qualifying equipment, machinery, and off-the-shelf software. It carries a dollar cap that adjusts annually for inflation and a phase-out threshold: once total qualifying property placed in service during the year exceeds a set amount, the maximum deduction shrinks dollar-for-dollar.
One catch matters at the partner level. The Section 179 deduction allocated to a partner cannot exceed that partner’s taxable income from all active trades or businesses. Excess carries forward. Because the test runs partner by partner, two partners in the same partnership can end up with different usable amounts.
Intangibles and Startup Costs
Acquired intangibles like goodwill, trademarks, customer lists, and covenants not to compete are amortized on a straight-line basis over 15 years from the month of acquisition.6Office of the Law Revision Counsel. 26 U.S. Code 197 – Amortization of Goodwill and Certain Other Intangibles7Internal Revenue Service. Intangibles
Startup and organizational costs have their own rule. A partnership can elect to deduct up to $5,000 of startup costs and up to $5,000 of organizational costs in the year the business begins. Each $5,000 allowance phases out once the respective costs exceed $50,000. Anything not immediately deductible is amortized over 180 months starting the month the business opens.
Three Hurdles Before a Loss Reduces Your Tax
An allocated loss on your K-1 does not automatically deduct. Partners must clear three tests in order, and a loss blocked at any stage is suspended and carried forward until the circumstances change.
Basis
The first test compares the loss to your outside basis in the partnership. Basis starts with the cash and property you contributed, increases with your share of income and partnership liabilities, and decreases with losses and distributions. Any allocated loss above your remaining basis at year-end is suspended and becomes usable when basis rises through future contributions, income allocations, or an increased share of partnership debt.
At-Risk
Even with basis, you can only deduct losses up to the amount you are personally at risk for. That includes cash and property you contributed plus partnership debt for which you are personally liable. Most non-recourse debt does not count, with one important exception: qualified non-recourse financing secured by real property does increase the at-risk amount. Losses blocked here are also suspended until the at-risk amount grows.
Passive Activity
The final test asks whether you materially participate in the partnership’s business. If you do not, the interest is passive, and any losses can only offset income from other passive activities. They cannot offset wages, salary, or investment income.
Several tests exist for material participation. The most common is the 500-hour test: participate for more than 500 hours during the tax year, and you are treated as a material participant.8Internal Revenue Service. IRS Tax Topic 425 – Passive Activities Losses and Credits Other tests apply when hours are lower but involvement is still substantial. Suspended passive losses carry forward indefinitely and become fully deductible when you dispose of your entire partnership interest in a taxable transaction.
The 20% QBI Deduction
Eligible partners can deduct up to 20% of their share of the partnership’s net business income on their personal return.9Office of the Law Revision Counsel. 26 U.S. Code 199A – Qualified Business Income The qualified business income deduction was originally scheduled to expire after 2025 but has been made permanent. It is claimed by the partner as a deduction from adjusted gross income on Form 1040, not at the partnership level.
QBI is the net amount of income, gain, deduction, and loss from the partnership’s trade or business.10Internal Revenue Service. Qualified Business Income Deduction Several items are excluded: guaranteed payments for services, capital gains and losses, interest income not properly allocable to the business, and any reasonable compensation paid to the partner. The partnership reports each partner’s share of QBI, W-2 wages, and unadjusted basis of qualified property on Schedule K-1.
Below a statutory taxable income threshold (adjusted annually for inflation), a partner generally receives the full 20% with no further limits. Above the threshold, W-2 wage and property caps phase in. Partners in specified service trades or businesses (law, accounting, health care, consulting, among others) face a steeper penalty: their deduction begins phasing out entirely once taxable income clears the threshold and is fully eliminated at the top of the phase-in range.
Once a partner is fully above the phase-in range, the deduction is capped at the greater of two amounts. The first is 50% of the W-2 wages the partnership paid that are allocable to the qualified business. The second is 25% of those W-2 wages plus 2.5% of the unadjusted basis (immediately after acquisition) of the partnership’s qualified property. A partnership with no employees and no significant property could see its higher-income partners’ QBI deduction drop to zero.
Retirement Contributions as a Deduction
Because partners are self-employed, retirement plans double as a major deduction. Two options cover most partnerships.
A SEP IRA allows contributions of up to 25% of a partner’s net self-employment income, capped at $72,000 for 2026. Net self-employment income for this purpose is Schedule K-1 net profit reduced by the deductible portion of self-employment tax. The partnership can set up the SEP and contribute for each partner, or partners can contribute on their own. The full contribution is deductible and reduces adjusted gross income.
A solo 401(k) fits partnerships where every worker is an owner. For 2026, a partner can defer up to $24,500 as pre-tax or Roth elective deferrals, and the partnership can add an employer profit-sharing contribution of up to 25% of the partner’s compensation. Combined, both sources cannot exceed $72,000. Partners aged 50 to 59 or 64 and older can add an $8,000 catch-up, and those aged 60 to 63 can add up to $11,250 if the plan allows.
Filing Deadline and the Late Return Penalty
Partnership returns are due March 15 following the close of the tax year, or the next business day if that falls on a weekend or holiday. For the 2025 tax year, the deadline is March 16, 2026.
The penalty for filing a late or incomplete Form 1065 is assessed per partner for each month or partial month the return is overdue, up to 12 months. A partnership that owes no tax still triggers the penalty if the return is late, and the total climbs quickly in partnerships with many partners. Issuing Schedule K-1s to each partner on time matters just as much, because partners cannot file accurately without them.