Q4 Estimated Taxes for US Online Sellers: When They Are Due

Quick answer: In the US, the fourth (Q4) estimated tax payment covers income earned from 1 September to 31 December and is due on 15 January of the following year. For 2026 income, that's Friday 15 January 2027. Online sellers who expect to owe tax beyond what's withheld elsewhere should pay estimated tax each quarter. Because Q4 includes Black Friday and Christmas, it's often the biggest payment of the year, so set money aside as you sell. This is general information, not tax advice.

Here's a pattern we see with US sellers every January. December was brilliant. Then the sales money got spent on restocking, ads and a well-earned break, and suddenly it's mid-January and a large tax bill is due on profits from November and December. The money was earned, just not set aside. A little planning in October avoids that panic.

Tekovex manages marketplace stores for UK and US sellers, and our client stores have passed £1 million in UK sales. We're not tax advisers, but we help sellers keep the clean sales and fee records that make this easy. Always confirm your situation with a tax professional.

2026 estimated tax due dates

The IRS uses these payment periods for calendar-year taxpayers (IRS):

• 1 January to 31 March: due 15 April 2026
• 1 April to 31 May: due 15 June 2026
• 1 June to 31 August: due 15 September 2026
• 1 September to 31 December: due 15 January 2027

If a due date falls on a weekend or legal holiday, the payment is on time if made on the next business day.

Who needs to pay estimated tax?

Generally, sole proprietors and single-member LLC sellers who expect to owe at least $1,000 in federal tax for the year, after withholding and credits, need to make estimated payments. That includes many people selling on Amazon, eBay, Etsy, TikTok Shop or their own store as a side business. States may have their own estimated tax rules too.

How to work out your Q4 payment

• 1. Track profit, not sales. Sales minus cost of goods, marketplace fees, shipping, ads and other expenses.
• 2. Include self-employment tax. Self-employed sellers pay Social Security and Medicare through self-employment tax, as well as income tax.
• 3. Use IRS Form 1040-ES or your tax software to estimate the amount due.
• 4. Check the safe harbor rules. You can generally avoid an underpayment penalty by paying at least 90% of this year's tax, or 100% of last year's tax (110% if last year's adjusted gross income was over $150,000). See IRS Publication 505.

Practical habits for Q4

• Move a set percentage of every payout into a separate tax account. Many sellers use 20–30%, but ask your accountant what fits your income.
• Download marketplace reports monthly, including fees and refunds.
• Keep receipts for stock, packaging, postage and software.
• Remember marketplaces report seller income to the IRS on Form 1099-K once you pass the reporting threshold.
• Pay through IRS Direct Pay or your IRS online account, and keep the confirmation.

What if you miss it?

The IRS may charge a penalty for underpaying estimated tax, even if you're due a refund when you file. The penalty is based on how much was underpaid and for how long, so paying late is still better than not paying.

Frequently asked questions

When are Q4 estimated taxes due for 2026?

15 January 2027, covering income from 1 September to 31 December 2026.

Do online sellers have to pay quarterly taxes?

Generally yes, if they expect to owe at least $1,000 in federal tax for the year after withholding and credits.

How much should I set aside for taxes as an online seller?

It depends on your profit and tax bracket. Many sellers set aside 20–30% of profit; confirm with a tax professional.

Can I skip the Q4 payment if I file early?

The IRS lets you skip the January payment if you file your return and pay all tax owed by 31 January. Check IRS guidance for the exact rule.

Does this apply to UK sellers?

No. UK sellers follow HMRC rules instead. See our guide to HMRC and online sales.

Want clean sales reports for tax time?

Tekovex manages Amazon, eBay, Etsy and TikTok Shop stores with clear monthly sales and fee reporting. See our Amazon services or book a free consultation.