If a client, nonprofit, or organization is asking you to fill out a W-9 for a reimbursement, it’s almost always because you aren’t their employee. When a business pays someone who isn’t on payroll, the IRS treats the whole payment as potentially reportable, including any portion labeled as expense reimbursement. The W-9 collects the Taxpayer Identification Number the payer needs to file a 1099 at year-end if your total payments cross the reporting threshold.1Internal Revenue Service. About Form W-9, Request for Taxpayer Identification Number and Certification
That’s the short answer. The longer one depends on whether you’re an employee, a contractor, a board member, a volunteer speaker, or a vendor, so it’s worth walking through what actually triggers the request.
Employees Usually Don’t Get This Request
If you’re a W-2 employee and your employer runs a standard expense reimbursement process, you shouldn’t be getting a W-9 request. Your employer already has your TIN from the W-4 you filed at hire, and reimbursements paid through a properly structured “accountable plan” aren’t treated as income at all. They stay off your W-2 and never become a 1099 issue.
An accountable plan has to meet three conditions under Treasury regulations: the expense must have a business connection, you must substantiate it with records like receipts, and you must return any advance that exceeded actual expenses within a reasonable time.2eCFR. 26 CFR 1.62-2 – Reimbursements and Other Expense Allowance Arrangements When all three are met, the reimbursement is excluded from wages.
If any one fails — a flat monthly car stipend with no mileage logs is the classic example — the payment becomes a “non-accountable” reimbursement, gets added to your taxable wages, and shows up on your W-2 with payroll taxes withheld.3Internal Revenue Service. IRS Publication 5137 – Fringe Benefit Guide Either way, an employee’s reimbursement doesn’t route through a W-9. So if you’re being asked for one, the more likely explanation is that the organization doesn’t consider you its employee.
Why Non-Employees Almost Always Get Asked
Independent contractors, freelancers, vendors, board members, and outside speakers all sit outside the payroll system. When a business pays someone in one of those categories, the IRS default is that the entire gross payment is potentially reportable on Form 1099-NEC (for services) or Form 1099-MISC (for categories like rent or legal fees).4Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC The payer doesn’t split your fee from your expenses on the form. It all goes into one box.
You handle the expense side on your own return. As a sole proprietor or contractor, you report the full amount on Schedule C as gross income and deduct the reimbursed business expenses against it.5Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship) The taxable amount ends up the same, but the paperwork lands on you rather than the payer.
A concrete example. A freelance photographer bills a company $1,500 for an event plus $700 for travel she paid out of pocket. The company cuts one check for $2,200. Because the total crosses the reporting threshold, the payer files a 1099-NEC for the full $2,200 and needs the photographer’s W-9 on file to do it. The photographer reports $2,200 as gross income on Schedule C and deducts the $700 in travel, leaving $1,500 in net taxable income.
The 2026 Threshold Doesn’t Eliminate the Request
For years the reporting threshold was $600. Starting with tax year 2026, it rises to $2,000 for most information returns, with inflation adjustments beginning in 2027.6Internal Revenue Service. 2026 Publication 1099
A higher threshold still doesn’t get you off the hook for the W-9. Payers have no way of knowing in March whether they’ll hire you again in September and push cumulative payments past $2,000. Collecting the form at the first payment is the only way they avoid scrambling later. And the IRS requires the W-9 before any reportable payment is made, not after totals are known.7Internal Revenue Service. Instructions for the Requester of Form W-9 Many organizations collect a W-9 for every non-employee payment regardless of size. That’s a policy choice, not overreach.
Can a Contractor Reimbursement Ever Be Tax-Free?
Sometimes. The IRS allows independent contractors to qualify for “working condition fringe benefits” under IRC Section 132, using requirements nearly identical to the accountable plan rules for employees. The payer has to require the money be spent on deductible business expenses, verify you actually did so, and collect back any excess.8Internal Revenue Service. Nonresident Aliens and the Accountable Plan Rules When all three are met, the reimbursement can be excluded from income and doesn’t need to be reported.
Most businesses skip that setup. It demands the same recordkeeping as an employee accountable plan, which cancels out the administrative simplicity of hiring a contractor in the first place. The standard workflow is to pay a gross amount, report it on a 1099, and let the contractor deduct the expenses. Which is why the W-9 lands in your inbox.
What Happens If You Refuse
Declining to fill out a W-9 doesn’t cancel the reporting obligation. It triggers backup withholding, and that’s worse for you than the form itself.
When a payee fails to furnish a TIN, the payer must withhold 24% of every reportable payment and remit it directly to the IRS.9Internal Revenue Service. Backup Withholding On that $2,200 photography job, you’d receive $1,672 instead of $2,200 and see $528 sent to the IRS as a prepayment of your tax. You can claim the withheld amount as a credit on your return, but the cash sits with the government until you do.
Payers also face personal liability for uncollected backup withholding if they don’t enforce it when required.7Internal Revenue Service. Instructions for the Requester of Form W-9 That’s why accounts payable departments won’t cut a check without a completed W-9. It isn’t bureaucratic stubbornness. It’s the payer protecting itself from a liability the IRS assigns directly to them.
Keeping Your SSN Off the Form
Most of the discomfort behind “why do I need to fill this out?” is really about handing your Social Security Number to a company you barely know. That concern is reasonable, and you do have one lever.
If you’re a sole proprietor with an Employer Identification Number, you can enter your EIN on the W-9 instead of your SSN. The IRS prefers sole proprietors use their SSN but accepts either. If you don’t have an EIN, you can apply for one through the IRS at no cost and get it issued immediately online. Using an EIN doesn’t change your tax obligations, and it keeps your SSN out of a filing cabinet you don’t control.
An LLC taxed as a sole proprietorship follows the same rule and can use its EIN. LLCs taxed as partnerships or corporations use the entity’s EIN by default.
The completed W-9 itself stays with the payer. It’s never filed with the IRS. It just sits in their records to support any 1099 they issue you. If a company asks you to email the form through an unsecured channel, it’s fair to ask for a secure upload portal or send it by fax, mail, or encrypted file instead.