Billable expense income is taxable in almost every case. When a client reimburses you for a cost you paid on their behalf, the IRS treats that reimbursement as part of your gross income under the rule that income includes “all income from whatever source derived.”1Office of the Law Revision Counsel. 26 U.S. Code 61 – Gross Income Defined The workable answer for most freelancers and small businesses is to report the full reimbursement as revenue and deduct the underlying cost, so you only pay tax on any markup. A narrow exception exists for true pass-through arrangements, but it rarely applies and it invites scrutiny.
How to Report Reimbursements Correctly
Accountants call the standard method “grossing up.” You record the full client reimbursement as revenue, record the original cost as a business expense, and let the two offset each other. Only the difference, if any, increases your taxable income.
Say you pay a $500 filing fee for a client’s project and bill the client $550. On Schedule C, the $550 goes on Line 1 as part of gross receipts. The $500 is then deducted as a business expense under supplies or cost of goods sold. Net taxable income from the transaction: $50.2Internal Revenue Service. Instructions for Schedule C (Form 1040)
The method works the same way with no markup. Bill the client exactly $500, report $500 in revenue, deduct $500 in expenses, and the net effect on your profit is zero. The transaction is a wash, but it’s a documented wash that matches the paper trail your client generates.
The Narrow Exception for Pass-Through Payments
A second approach exists where you skip both the income and the deduction. The outlay is booked as an accounts receivable, and when the reimbursement arrives, the receivable clears. Neither the expense nor the payment shows up on your income statement.
This treatment is only defensible when you meet all three of these conditions:
- No markup. The client is billed the exact amount you paid, to the penny.
- No primary liability. If the bill goes unpaid, the vendor pursues the client, not you.
- A clear agency relationship. Your contract establishes that you’re paying on the client’s behalf, not buying something for resale or incorporating it into your own service.
Very few freelancer-client relationships meet all three. If you signed the contract with the vendor and paid with your own card, you are the primary obligor, and the grossing-up method is the correct one regardless of whether you marked up the cost. The IRS can reclassify a netted transaction as taxable income if it concludes you were the primary buyer rather than an intermediary.
Why the 1099 Usually Settles the Question
Even when netting is theoretically defensible, the 1099 your client files often makes it impractical. If a client pays you $10,000 in fees plus $2,000 in expense reimbursements, their 1099-NEC typically reports $12,000. The IRS instructions tell payers to include reimbursements on the 1099-NEC whenever the contractor hasn’t “accounted to the payer” for those expenses, and most clients include everything to be safe.3Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC
If you then report only $10,000 on Schedule C because you netted out the reimbursements, the IRS sees a $2,000 gap between what your client reported paying and what you reported earning. That mismatch can trigger an automated notice, and answering it means documenting the agency arrangement under audit conditions.
For tax years beginning after 2025, the Form 1099-NEC reporting threshold increased from $600 to $2,000.4Internal Revenue Service. 2026 Publication 1099 Falling below the threshold doesn’t change whether the income is taxable. It only changes whether a third party sends the IRS a copy.
Self-Employment Tax Is on the Line Too
Misclassifying reimbursement income doesn’t just affect income tax. Self-employed individuals pay both the employer and employee shares of Social Security and Medicare, for a combined rate of 15.3% on net self-employment earnings.5Internal Revenue Service. 2026 Publication 15-A
Used correctly, the grossing-up method leaves your SE tax base untouched by pure reimbursements. A $500 expense reimbursed at $500 nets to zero and adds nothing to SE tax. But if you net a transaction that shouldn’t have been netted and can’t substantiate the agency relationship, the IRS may add the full reimbursement to your net earnings. On a $10,000 reclassification, that’s roughly $1,530 in additional self-employment tax before income tax and penalties.
Documentation That Holds Up
The documentation burden is heaviest when you net reimbursements off your return, because you’re claiming an exclusion from income. But even the grossing-up method needs records that connect each reimbursement to its cost.
Keep these for every billable expense:
- The original vendor receipt or invoice, showing what you paid, to whom, and when.
- Your client invoice with reimbursable expenses itemized separately from your service fee. A lump-sum invoice that bundles everything together looks like a sale, not a pass-through.
- A written engagement letter or contract specifying which expense categories are billable and whether they’ll be reimbursed at cost or with a markup.
- Bank or credit card statements showing the outgoing payment and the incoming reimbursement, with dates close enough to establish the connection.
If the IRS challenges a netted arrangement, they will look at who was primarily liable to the vendor, whether any expenses were marked up, and whether the documentation tells a consistent story. Missing one link, such as an invoice that doesn’t separately list the expense, can result in the entire reimbursement being reclassified as taxable gross income with no offsetting deduction, because you never claimed one.
Penalties for Getting It Wrong
The IRS imposes a 20% accuracy-related penalty on any underpayment resulting from negligence or a substantial understatement of income tax.6Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments Incorrectly netting $15,000 in reimbursements off your return can produce several thousand dollars in understated tax. The 20% penalty is stacked on top, plus interest running from the original due date.
The reverse mistake costs you too. Report reimbursements as income but forget to deduct the underlying expenses, and you overpay. The IRS won’t penalize an overpayment, but you’re out the money until you file an amended return. Grossing up with clean documentation is the simplest way to get the number right the first time.
When the Client Doesn’t Pay You Back
If you front an expense expecting reimbursement and the client never pays, whether you can write off the loss depends on your accounting method. Most sole proprietors use the cash method, and the IRS is direct about the limitation: cash-method taxpayers generally cannot take a bad debt deduction for unpaid amounts because the money was never included in income to begin with.7Internal Revenue Service. Topic No. 453, Bad Debt Deduction
On the cash method, an unreimbursed expense you paid out of pocket for a client is still deductible, just not as a bad debt. It’s deductible as the underlying expense itself: travel, supplies, filing fees, whatever category fits. Accrual-method businesses that already reported the expected reimbursement as income can potentially claim a business bad debt deduction, because the IRS requires prior inclusion in gross income before allowing one.7Internal Revenue Service. Topic No. 453, Bad Debt Deduction
A Note on Sales Tax
Sales tax on reimbursed expenses is a state-level question, and the answer varies. Many states require sales tax on the total amount billed to a client when the reimbursed expense is part of a taxable service. True pass-through expenses where you act purely as a collection agent, such as a government filing fee paid on a client’s behalf, are typically exempt. The line between “part of the service” and “pure pass-through” varies by state, so check your state Department of Revenue’s guidance for the specific expense categories you bill regularly.