October 15 Tax Extension Deadline: A Reseller's 5-Day Filing Plan

Filed a tax extension for your eBay or Facebook Marketplace reselling? The October 15, 2026 deadline, what late filing costs, and a 5-day plan to finish.

If you asked for an extension back in April because your reselling records were not ready, the extra six months end on Thursday, October 15, 2026. That is the last day to file a 2025 federal return on extension without a late-filing penalty, and it lands right as Q4 sourcing and listing take over your week.

Most resellers on extension are in the same spot: the sales are easy to find, because eBay kept them, but the costs are scattered. What did the inventory cost? How many miles went to auctions and the post office? What was still on the shelf on December 31? This article is a plan for getting from a pile of reports to a filed return in the days that are left, with the real cost of missing the date.

This is general information, not tax advice. Confirm your situation with a tax professional.

What October 15 does and does not cover (as of October 2026)

The IRS is plain about it on its extension page: an extension gives you until October 15 to file. It was never an extension to pay. Any tax you owed for 2025 was due on April 15, 2026, and interest plus a late-payment penalty have been running on any unpaid balance since then.

Three situations change the picture:

• You are due a refund. The late-filing penalty is a percentage of unpaid tax, so there is nothing to charge it on. You should still file, because that is the only way to get the money.
• You never filed an extension. Then October 15 is not your deadline; April 15 was. File as soon as you can anyway. Penalties and interest keep growing until you do.
• You were in a federally declared disaster area. The IRS says you may have more time; check its disaster relief page for your county.

What missing the deadline costs, in dollars

The IRS charges two separate penalties, and the gap between them is the whole reason to file on time even if you cannot pay.

• Failure to file: 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. If a return is more than 60 days late, the minimum penalty for returns due in 2026 is $525 or 100% of the unpaid tax, whichever is less.
• Failure to pay: 0.5% of the unpaid tax per month or part of a month, up to 25%. In a month where both apply, the filing penalty is reduced by the payment penalty, so the combined charge is 5%.
• Interest: 7% per year, compounded daily, for the quarter that began October 1, 2026, per the IRS fourth-quarter rate announcement.

Worked example: a reseller who owes $1,500

Say your 2025 reselling profit leaves a $1,500 balance you have not paid yet.

1. File and pay by October 15. Failure to pay has run for six months: 6 × 0.5% × $1,500 = $45, plus roughly $50 of interest at the current 7% rate. About $95 total.
2. File by October 15, pay on December 10. Two more months of failure to pay: 8 × 0.5% × $1,500 = $60, plus interest.
3. File and pay on December 10. The same $60, plus failure to file for two months at 4.5% each: 2 × 4.5% × $1,500 = $135. Now you are at $195 plus interest.
4. File after December 14. The return is more than 60 days late, so the minimum failure-to-file penalty applies: the lesser of $525 or the $1,500 owed. That is $525 for filing, on top of the payment penalty and interest.

Filing on time costs nothing extra, even if you cannot pay. On a $1,500 balance, filing two months late adds $135; filing more than 60 days late adds at least $525.

If you cannot pay the full balance, file anyway and look at an IRS payment plan. The IRS says that if you filed on time and have an approved plan, the failure-to-pay rate drops to 0.25% a month while the plan is in effect.

The 2025 numbers a reseller needs on the return

A reseller's return is mostly a Schedule C. These are the 2025 figures that are easy to get wrong when you are rushing:

• Gross sales from every channel. For 2025, a marketplace has to send a Form 1099-K only when payments were over $20,000 in more than 200 transactions, as the IRS explains on Understanding your Form 1099-K. The same page says you must report your income whether or not you get the form. So a seller with $14,000 on eBay and $3,000 of local Facebook Marketplace cash sales reports all $17,000, with no form for either. Our 1099-K guide covers the details.
• Mileage at the 2025 rate: 70 cents a mile. The IRS standard mileage rates page lists 70 cents for 2025 business driving. The 72.5 and 76 cent rates you may have seen are for 2026 and do not belong on this return.
• Cost of goods sold, not purchases. You deduct the cost of items that sold in 2025. Inventory still on the shelf on December 31, 2025 is ending inventory and carries into 2026. Our Schedule C guide for resellers walks through Part III.
• Self-employment tax. The IRS self-employment tax page puts the rate at 15.3% and says it applies once net earnings reach $400. Schedule SE applies it to 92.35% of net profit, so $6,000 of reselling profit is $6,000 × 92.35% × 15.3% = $847.77, before income tax.

A five-day plan to rebuild 2025 and file

Saturday: pull every sales record

Download your 2025 eBay Transaction report from Seller Hub (Payments, then Reports; you may need more than one date range to cover January 1 through December 31). It lists each order with the fees, shipping labels and refunds eBay took out. For Facebook Marketplace, pull your shipped-order payout history, then list local cash sales from Messenger threads, your calendar and bank deposits. Do the same for Mercari, Poshmark or Whatnot if you sold there.

Sunday: rebuild what the inventory cost

This is the slow part. Gather auction invoices, liquidation receipts, thrift and garage-sale notes, and card statements. Match costs to the items that sold in 2025. For a pallet or lot, split the price across the items in it. If a cost is truly gone, use the best honest figure you can support and keep a note of how you got it.

Monday: expenses and miles

Add up shipping supplies, storage, subscriptions and any postage bought outside eBay. Labels bought through eBay are already in the Transaction report, so do not count them twice. Rebuild mileage from dated records: auction pickup dates, post office receipts, Google Maps Timeline. Each trip needs a date, miles and a business purpose. Multiply by 70 cents.

Tuesday: ending inventory and the Schedule C totals

Count, or reconstruct from purchase records, what was unsold on December 31, 2025, at what you paid. Then: purchases minus ending inventory (plus beginning inventory, if you had any) equals cost of goods sold. Our own first eBay order shipped on November 30, 2025; a short first year like that is exactly where ending inventory matters, because most of what you bought had not sold yet.

Wednesday: file

Hand the totals to your tax professional or file yourself. The IRS says its Free File guided software is open to filers with adjusted gross income of $89,000 or less; confirm the provider you pick supports Schedule C. E-file, save the acceptance confirmation, and pay what you can with the return. That leaves Thursday the 15th as a cushion, not a plan.

Do not let 2026 turn into the same scramble

You are now more than nine months into the 2026 tax year, with the busiest quarter still ahead. Three things keep next year from repeating this week:

• Record cost when you buy, not when you file. Every auction invoice and thrift receipt goes in the day it happens.
• Log miles as you drive them. The 2026 business rate is 72.5 cents through June 30 and 76 cents from July 1.
• Put the next due date on the calendar. The fourth-quarter estimated tax payment for 2026 is due January 15, 2027. Your holiday profit is what it is based on.

If you get stuck sorting a 2025 report into the right columns, you get real-person support from the owner, Johnathon Lawson: [email protected].

Frequently asked questions

Is October 15, 2026 the deadline to pay my 2025 taxes too?

No. The extension only moved the filing date. Payment was due April 15, 2026, and the IRS has charged interest and a 0.5% per month failure-to-pay penalty on any unpaid balance since then.

What if I cannot pay what I owe by October 15?

File on time anyway. The failure-to-file penalty (5% a month) is ten times the failure-to-pay penalty (0.5% a month). Then pay what you can and look at an IRS payment plan for the rest.

Do I have to report eBay or Facebook Marketplace sales if I did not get a 1099-K?

Yes. For 2025 a platform only had to send a 1099-K above $20,000 and 200 transactions, but the IRS says all income must be reported whether or not you receive the form. Local cash sales count too.

What mileage rate do I use on a 2025 return?

70 cents per mile for business driving in 2025. The 2026 rates (72.5 cents through June 30, 76 cents from July 1) apply to the return you will file next year.