If you have never had a payment come in short, this article is insurance. Read the last section and file the paperwork before it happens.

The invoice was $4,000. The deposit was $3,040. Nobody called to explain, and the client's accounts team says it was correct.

It was. And the missing $960 is yours.

The short answer
What it is Backup withholding — tax withheld by the payer
Rate A flat 24%
Where it goes To the IRS, in your name
Where it shows up Box 4 of the 1099
What you do with it Claim it as federal income tax withheld on your return
What prevents it A signed Form W-9 before the first payment

It is not a fee

Topic 307 is unambiguous about both the obligation and the destination:

"…the payer must withhold at a flat 24% rate…"

And, crucially:

"If your Form 1099 shows an amount withheld under the backup withholding rules, report the amount as federal income tax withheld on your income tax return for the year you received the income."

So the money went to your tax account, not to the client and not into a void. When you file, it is credited exactly like an employee's withholding — and if you over-withheld relative to what you owe, it comes back as refund.

That is worth knowing on the day it happens, because the instinct is to argue with the client about a payment they were legally required to make.

The one thing to do firstCheck box 4 of the 1099 when it arrives. That is where the withheld amount appears, and it is the figure you claim. A client who withheld but never filed the form has created a problem worth chasing immediately.

The four triggers

Topic 307 lists them, and they are not all equally likely:

  1. You did not give the payer your TIN in the required manner. This is nearly all real cases, and it usually means no W-9 was ever signed.
  2. The IRS told the payer your TIN is incorrect. A name and number that do not match — a married name, a business name against a personal SSN, a typo.
  3. The IRS told the payer to start withholding because you underreported interest or dividends. This one is slow and loud: "The IRS will do this only after it has mailed you four notices over at least a 120-day period."
  4. You failed to certify that you are not subject to withholding for that underreporting.

Trigger 3 never arrives as a surprise. Triggers 1 and 2 almost always do, because the paperwork that prevents them is the paperwork nobody chases until January.

Stopping it

"To stop backup withholding, you'll need to correct the reason you became subject to backup withholding in the first place."

For the common case that means giving the payer your correct name and TIN and certifying it — which is precisely what Form W-9 does. One form, signed once, per client.

One detail worth having in advance:

"If you receive a second notice from that payer, you'll need to provide verification of your correct name and TIN."

A first notice is fixed by telling them again. A second notice needs proof — a Social Security card or an IRS letter confirming your EIN. Knowing that on the day the first notice arrives is the difference between a two-minute fix and a scramble.

If you are the one paying

This site's readers are usually on the receiving end, until the year they hire someone. Then the obligation flips, and it is heavier than it looks.

Do this When
Collect a signed W-9 Before the first payment, not in January
Run TIN Matching through IRS e-Services Before filing, free
Withhold 24% if the W-9 is missing or wrong From the payment itself
Deposit what you withheld and report it on Form 945 On the schedule that applies to you

The reason to collect the W-9 first is simple arithmetic: once you have paid somebody in full without one, you cannot withhold from money you no longer hold — and the liability for not withholding is yours, not theirs.

TIN Matching is the part almost nobody uses. It confirms a name and number pair before you file, which prevents the IRS notice that starts the whole sequence in the first place.

The sequence, end to end

  1. No W-9 on file when the first payment goes out.
  2. The payer withholds 24%, correctly.
  3. A 1099 arrives in January with an amount in box 4.
  4. You claim it as federal income tax withheld and it reduces what you owe, dollar for dollar.
  5. You send a W-9 and it never happens again with that client.

Five steps, and the first one is the only one that was avoidable. It takes two minutes and it is the cheapest piece of admin in independent work.

Track it now. Thank yourself in April.

Common questions

My client paid me 24% less than the invoice. Can they do that?
If backup withholding applies, they are required to. Topic 307 says the payer "must withhold at a flat 24% rate" when you have not given your TIN in the required manner, among other triggers. It is not a discount they chose to take.
Is that money gone?
No. Topic 307: "If your Form 1099 shows an amount withheld under the backup withholding rules, report the amount as federal income tax withheld on your income tax return for the year you received the income." It is a prepayment of your own tax, and it appears in box 4 of the form.
What triggers it?
Four things, per Topic 307: you did not give the payer your TIN in the required manner; the IRS told the payer your TIN is wrong; the IRS told the payer to start withholding because you underreported interest or dividends; or you failed to certify that you are not subject to it for that underreporting.
How do I stop it?
Fix the reason. For the common case that means giving the payer your correct name and TIN and certifying it — which is what Form W-9 is. Topic 307 notes that on a second notice from that payer, you must provide verification of your name and TIN, not just restate them.
How fast does the IRS act before ordering withholding for underreporting?
Not fast. Topic 307: "The IRS will do this only after it has mailed you four notices over at least a 120-day period." That route never arrives unannounced.
Which payments can it apply to?
Most kinds reported on a 1099 — nonemployee compensation on 1099-NEC, rents and royalties on 1099-MISC, interest, dividends, broker proceeds, and payment card and third party network transactions on 1099-K.
I am the one paying contractors. What do I do?
Collect a signed W-9 before the first payment, not in January. The obligation to withhold is yours, and so is the liability if you should have withheld and did not.
Can I check a TIN before I file?
The IRS offers free TIN Matching through its e-Services, which confirms whether a name and number pair matches before you send a form. Almost nobody uses it, and it prevents the notice that starts this whole sequence.

This article is for educational purposes only and does not constitute tax, legal, or financial advice. Consult a qualified tax professional about your situation.

Official sources