Every seller who's set up payouts on eBay or Shopify Payments has typed a Social Security number or EIN into a form at some point and moved on. Most never think about it again, because for most sellers it never comes up again. But there's a specific failure mode sitting behind that field — a name and taxpayer ID that don't match IRS records, or no ID on file at all — and when it triggers, it doesn't send you a warning letter first. It takes 24% of your next payout before you ever see it, on the gross sale amount, not your profit. New federal regulations that took effect this month change exactly who that applies to.
Two different rules, easy to conflate
Sellers usually run into two separate legal requirements under one "give us your tax info" prompt, and they're not the same rule with different names — they're different laws with different triggers.
The first is identity verification. Because eBay and Shopify Payments move money on your behalf, both are subject to Bank Secrecy Act customer- identification requirements — the same category of rule that makes a bank ask for ID before opening an account. That's why a taxpayer ID gets requested early, often well before a seller has any realistic chance of hitting a tax-reporting threshold. It's about verifying who's being paid, not about triggering a tax form.
The second is backup withholding under Internal Revenue Code Section 3406 — a completely different mechanism, with its own trigger, that's what actually pulls money out of a payout.
What changed on August 10, 2026
Backup withholding on third-party network transactions used to run on its own separate logic from 1099-K reporting. That gap closed this month: the Treasury and IRS published final regulations under Treasury Decision 10053, effective August 10, 2026, that tie backup withholding for third-party settlement organizations — eBay, Shopify Payments, PayPal, and similar platforms — to the same threshold that now governs the 1099-K itself: $20,000 in gross payments and more than 200 transactions in a calendar year. Below that line, a TPSO generally isn't required to backup-withhold on a seller's payments at all, missing or mismatched taxpayer ID or not.
That $20,000-and-200-transaction number is itself the result of a 2025 law change worth knowing if you haven't run into it: the One Big Beautiful Bill Act, signed July 4, 2025, repealed the lower $600 reporting threshold that had been phasing in since the 2021 American Rescue Plan Act, and reverted 1099-K reporting to the pre-2022 level — retroactively, back to 2022. The August 2026 backup-withholding regulations simply align the withholding trigger to that same reverted number, so the two rules that used to be able to disagree with each other now move together.
Practically: a seller doing $9,000 a year on eBay with a taxpayer ID that doesn't match anything on file is, under the current rule, not going to see backup withholding kick in over that mismatch. A seller doing $35,000 a year across 300-plus transactions with the same unresolved mismatch is exactly who this rule is built to catch.
What actually triggers it
Backup withholding isn't triggered by low sales, high sales, or anything about the transaction itself. It's triggered by one of two things on the account:
- No taxpayer ID on file at all — a seller who never completed the W-9
- step, or whose payout setup somehow left it blank.
- A name-and-TIN combination that doesn't match IRS records — most
- commonly a seller who registered under a store or DBA name ("Joe's
- Vintage Finds") instead of the legal name tied to their Social Security
- number, or an EIN entered against a business name that doesn't match what
- the IRS has on record for that EIN.
Platforms are required to notify a seller and give them a chance to correct a mismatch — that's what a "B-Notice" is — before withholding actually starts. But if it isn't corrected, once a seller crosses the $20,000/200- transaction line, the platform starts withholding on payments going forward, not just on the transaction that finally tipped the count.
The 24% comes off the gross, before fees
This is the detail that surprises sellers who've never hit it: backup withholding is calculated on the same gross number that shows up on a 1099-K — the total the buyer paid, including shipping and any tax collected, before eBay's or Shopify's own selling fees come out of it. It isn't 24% of your profit, and it isn't even 24% of what your payout would otherwise have been after fees. A $200 sale with $30 in platform fees already baked in has $48 withheld against the full $200, not against the $170 you'd have actually been paid.
And once it's withheld, the platform can't give it back to you directly — not even if the buyer returns the item. The money has already gone to the IRS. Getting it back means claiming it as a credit on your own tax return the following year: it shows up in the federal-withholding box on your 1099-K, you enter it as federal income tax withheld on Form 1040, and it reduces what you owe or comes back as part of your refund. Correct, but slow — the mechanism is the same one that makes an eBay payout hold a real cash-flow problem even when the sale itself was never in question: the money is legitimately yours, it just isn't available to you on the timeline your sourcing and bills run on.
A worked example
Say a seller crosses $20,000 in eBay sales and 210 transactions for the year, and their account has run for three years under a store name that never quite matched the SSN behind it — close enough that nobody at eBay flagged it during onboarding, but not an exact match against IRS records.
- eBay sends a B-Notice asking for a corrected W-9. The seller misses it,
- or assumes it's routine.
- Backup withholding starts on subsequent payouts: 24% of the gross sale
- amount on every transaction going forward, not retroactively on the first
- $20,000.
- The next $600 sale (item plus shipping) generates a payout that's $144
- short of what the seller expects, on top of eBay's normal final value
- fee already having reduced it.
- That $144 isn't gone — it'll show up as federal tax withheld on the
- 1099-K the following January, and reduce the seller's actual tax bill
- dollar for dollar when they file. But between the sale and the following
- tax season, it's cash the seller doesn't have, sitting against a tax
- liability that may end up smaller than what was withheld.
Fix the W-9 mismatch the week the B-Notice arrives, and none of this happens. Ignore it, and it runs on every payout until it's corrected.
What to actually do
- **Confirm the name on your eBay or Shopify Payments account is your
- legal name (or your business's legal name against its EIN)** — not a
- store name or DBA — matching exactly what the IRS has on file for that
- SSN or EIN.
- Don't ignore a B-Notice or a "verify your tax information" prompt.
- It's the platform giving you the chance to fix a mismatch before
- withholding starts, not a routine notification to dismiss.
- **If you're getting close to $20,000 and 200 transactions in a year,
- check your taxpayer info before you cross it**, not after a payout comes
- up short. The threshold is what activates the rule; fixing a mismatch
- after the fact stops future withholding but doesn't return what's already
- gone to the IRS.
- Don't expect a refund from the platform on a withheld amount, even on
- a canceled or returned sale. It's a tax-return line item, not a
- correctable transaction.
PalmFlow tracks your real payout against what a sale should have paid out at eBay's normal fee rate, so an unexpected 24% cut from backup withholding shows up as a real, visible gap instead of a payout that just looks wrong for no obvious reason. It doesn't collect your W-9, verify your taxpayer ID, or interact with eBay's or Shopify's compliance systems in any way — that setup lives entirely on the platform side. Free plan, 50 items, no card.
Disclaimer: this is general information, not tax advice. Backup withholding regulations, the 1099-K threshold, and the taxpayer-ID verification process are IRS and platform policy, subject to further change — confirm your own account status directly with eBay or Shopify, and check current guidance at IRS.gov, before assuming how any of this applies to your numbers.