Quarterly estimated taxes for resellers: what you owe and when

Every April, the same thing happens in reseller forums: someone posts their tax bill, and underneath it, a smaller line they didn't expect — a penalty for underpayment. Not because they owed too much. Because they paid it all at once instead of spreading it across the year like the IRS expects.

If you're selling as a business (not just occasionally clearing out a closet), you're probably supposed to be paying quarterly. Here's what that actually means, with the current numbers.

Why resellers owe quarterly at all

The US tax system is pay-as-you-go. When you have a job, your employer withholds tax from every paycheck automatically. When you're self-employed — which is what you are the moment reselling is a business and not a hobby — nobody withholds anything. The IRS still wants its money on the same schedule, so it asks you to estimate and pay it yourself, four times a year.

Skip it, and even if you pay your full tax bill correctly by April, you can still owe an underpayment penalty for not paying it on time throughout the year.

Do you actually have to?

The rule of thumb: if you expect to owe $1,000 or more in tax for the year after subtracting withholding and credits, you're supposed to make estimated payments. Most resellers doing more than a few thousand dollars a year in profit clear that bar easily, because there's no withholding on marketplace income at all.

This applies whether you're a sole proprietor or a single-member LLC that hasn't elected corporate tax treatment — the IRS treats a default single-member LLC the same as a sole proprietor for this purpose. There's no reseller carve-out. Schedule C income is Schedule C income whether it came from eBay, a flea market, or a garage.

The 2026 due dates

Estimated tax payments aren't quarterly in the calendar sense — the periods are uneven lengths, which trips people up:

• Q1 2026: due April 15, 2026
• Q2 2026: due June 15, 2026
• Q3 2026: due September 15, 2026
• Q4 2026: due January 15, 2027

If a due date lands on a weekend or holiday, it rolls to the next business day. If you file your full return and pay what's owed by February 1, 2027, you can skip the Q4 payment entirely.

How much to actually pay: the safe harbor

You don't need to predict your tax bill to the dollar. The IRS gives you a safe harbor — pay enough and you owe no penalty even if your final number is higher:

• Pay at least 90% of what you'll owe for the current year, or
• Pay 100% of what you owed last year (or 110% if your prior-year
• adjusted gross income was over $150,000)

whichever number is smaller. The second option is the easier one to plan around if your income is roughly steady: take last year's tax bill, divide by four, pay that each quarter, done.

What self-employment tax actually costs you

This is the number that catches new resellers off guard. On top of ordinary income tax, self-employment income owes self-employment tax: 15.3% — 12.4% for Social Security and 2.9% for Medicare — calculated on 92.35% of your net profit. The 12.4% portion stops once your total earnings for the year cross the Social Security wage base, which is $184,500 for 2026; the 2.9% Medicare portion has no cap.

A worked example: say your Schedule C shows $30,000 in net profit for the year — after cost of goods, platform fees, shipping, and mileage, not your gross sales.

• Net earnings subject to SE tax: 92.35% × $30,000 = $27,705
• Self-employment tax: 15.3% × $27,705 = ≈$4,239
• You then owe ordinary income tax on top of that, at your regular bracket
• (you do get to deduct half of the SE tax as an above-the-line adjustment,
• which softens it slightly)

That's real money leaving before you've paid a cent of income tax, and it's the piece resellers most often forget to set aside for.

What underpaying actually costs

If you skip estimated payments or pay too little, the IRS charges interest on the shortfall, not a flat fee. The rate resets every quarter and is tied to the federal short-term rate plus 3 points — for the current quarter (July through September 2026) it's 7% on individual underpayments, compounded daily, up from 6% the prior quarter. Check the IRS's quarterly interest rate page for the number in whatever quarter you're reading this, because it moves.

It's not devastating on a small shortfall, but on a few thousand dollars of underpayment held for months, it adds up to real dollars for no benefit — you're paying to delay a bill you owed anyway.

A workflow that actually works

• Set aside a percentage of profit as it comes in, not at tax time.
• Something in the 25–30% range covers SE tax plus income tax for most
• resellers in typical brackets — a CPA can tell you your actual number.
• Use last year's tax bill ÷ 4 as your default quarterly payment if your
• business is roughly steady, per the safe harbor above.
• Pay through IRS Direct Pay or EFTPS, not a paper check with Form
• 1040-ES — it's free, instant, and gives you a confirmation number.
• Recalculate if a quarter is way off pace. A huge Q4 sourcing haul that
• sells through in January doesn't need to change your Q3 payment, but a
• genuinely bigger year should bump what you set aside going forward.

The part that actually determines whether any of this is accurate is your profit number — and that's where most resellers' math quietly breaks. If you're estimating profit off gross sales instead of sales minus fees, shipping, and real cost basis, you're either setting aside too little (and meeting the underpayment penalty later) or too much (and starving your sourcing budget for no reason).

PalmFlow tracks cost basis per item and fees per sale, so the profit number you're setting tax money aside against is your real number, not a gross-sales guess. Free plan, 50 items, no card. If you're also trying to make sense of 1099-K reporting, we covered that here.

Disclaimer: this is general information, not tax advice. Your safe harbor number, bracket, and deductions are specific to you — talk to a CPA, and check IRS.gov for the current due dates and rates before you pay.

Published by PalmFlow. We build inventory software for resellers.