What Is Actually Due on October 15 If You Filed an Extension?

If you filed for an extension this year, the IRS is explicit about what you bought: "This gives you until October 15 to file without penalties." What it does not say, and what most people assume, is that the money moved too.

It did not. The same page is equally plain: "Make sure you pay any tax you owe by the April filing date. The extension is only for filing your return."

Tax ID

Get your ITIN.

The taxpayer ID for non-residents, handled end to end.

Begin

01The Distinction That Costs People Money

An extension is a filing accommodation, not a payment plan. The obligation to pay crystallised in April. Every month since, interest has been running on the unpaid balance, and in most cases a failure-to-pay penalty alongside it.

This catches non-residents more often than it catches anyone else, and the reason is structural rather than careless. A founder in Bogotá or Madrid whose accountant is still assembling US paperwork reasonably concludes that nothing is due until the paperwork is. The extension appears to confirm it. The interest accrues quietly in the background and surfaces months later attached to a notice.

02What Else Lands on the Same Date

For anyone with foreign financial accounts, the FBAR carries an automatic extension to the same October date. There is no form to file for it and no request to make. It simply moves, which means it is easy to forget that it moved at all. We have written separately on whether your company's foreign accounts require one.

A foreign-owned single-member LLC has its own obligation on Form 5472, attached to a pro forma return, and the penalty regime there is unusually severe relative to the size of most such companies. That deadline follows the entity's own calendar rather than the individual one, which is precisely why the two get confused.

03What a Sensible Position Looks Like Now

If a payment was made in April on a reasonable estimate, the exposure is limited to interest on whatever the estimate understated. That is usually a manageable number and it stops growing the moment the balance is settled.

If no payment was made because the return was not ready, the position is different, and the right instinct is to pay something against the estimated balance now rather than to wait for the return to be finished. Interest is charged on the outstanding balance, so reducing the balance reduces the accrual immediately, whether or not the paperwork is complete.

Taxes

File your US taxes.

Federal returns prepared by our team.

Begin

04The Part Worth Planning Around

October is not a deadline in the sense that April was. It is the end of an accommodation that was always narrower than it looked. Treating it as a second April is the error, and it is an expensive one because the cost is invisible until the notice arrives.

For anyone carrying a US entity from abroad, the more useful exercise is not to mark the date but to ask which of your obligations run on the individual calendar and which run on the company's. Those two calendars diverge, and the assumption that they move together is what produces most of the surprises we are asked to unwind.