Sooner or later someone pays for a business expense out of their own pocket: a manager buys supplies on a personal card, a technician drives their own truck to a job, an S corp owner works from a home office. How you pay them back decides whether the money is a tax-free reimbursement or taxable wages.
The difference comes down to whether you reimburse under an accountable plan. Here is what that means, what the IRS requires, and how to keep the books right.
What an accountable plan is, and why it matters
An accountable plan is an arrangement for reimbursing employees' business expenses that meets three IRS requirements. When it does, the reimbursement is deductible to the business, it is not wages, and it stays off the employee's W-2. No withholding and no payroll taxes apply.
When an arrangement fails those requirements, it is a nonaccountable plan. Every dollar paid under it is treated as wages: subject to income tax withholding, Social Security and Medicare, and reported on the W-2. A flat $300 monthly 'car allowance' with no mileage records is the classic example. The employee is also usually worse off, because employees generally cannot deduct unreimbursed work expenses on their own federal returns.
This matters most for S corporation owners. If you own an S corp and work in it, you are an employee of your company. Personal-card business purchases, business miles in your own car, and a share of your home office costs should come back to you as documented reimbursements, not as loose draws or unexplained transfers that your CPA has to sort out in March.
The three requirements
1. Business connection. The expense has to be one the employee paid or incurred while performing services for the business: mileage to a job site, a hotel for a trade show, materials for a repair. Personal costs do not qualify because someone submits a receipt.
2. Substantiation within a reasonable time. The employee has to account for each expense: the amount, the date, the place, and the business purpose, with receipts where required. For mileage, that means a log of dates, destinations, purposes, and miles, reimbursed at a rate no higher than the IRS standard mileage rate for the year. The IRS treats substantiation within 60 days after the expense as reasonable.
3. Return of any excess. If you advance money and the employee spends less, they have to return the difference within a reasonable time; the IRS safe harbor is 120 days. An advance should also be reasonably close to when the expense will occur, generally no more than 30 days before.
The regulations do not require a formal plan document, but putting the policy in writing is the simplest proof that the arrangement exists. A one-page policy covering what qualifies, what documentation is required, the deadline for submitting it, and how advances are settled is enough for most small businesses. Then follow it, including for yourself.
How to record reimbursements in your books
Book each reimbursement to the expense category it actually belongs to: supplies, travel, vehicle or mileage, office expenses. Avoid a catch-all 'Reimbursements' account. A $140 hardware store run reimbursed to a technician is a $140 supplies expense, the same as if the company card had paid it.
Keep reimbursements out of wages. If you pay them through your payroll system, use a nontaxable reimbursement item, not an addition to gross pay. If you pay them separately, attach the expense report and receipts to the payment so the documentation travels with the transaction.
Watch for two problems at month end. Personal-card purchases that were reimbursed and also entered from a receipt get counted twice, so reconcile the reimbursement payments against the expenses recorded. And advances that were never settled should not sit forever as a vague receivable. Collect the excess, or have your accountant treat it as wages before year-end payroll closes.
Getting it set up and keeping it clean
An accountable plan only works if the paper trail is kept month by month. Rebuilding mileage logs and receipts in December defeats the substantiation requirement, and it is exactly what an examiner looks for. If you are an S corp owner, talk to your CPA about what your company should reimburse you for, including the home office.
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