Who actually files Form 3520-A, and why is a calendar-year trust's deadline before my tax return?

The foreign trust files it, the trustee signs it, and it’s due the 15th day of the 3rd month after the trust’s year end (15 March for a calendar-year trust). That deadline is separate from yours and lands first for a calendar-year trust and owner. If the trust never files, the US owner attaches a signed substitute to their Form 3520. Check scope first: certain Canadian plans, RRSPs and RRIFs included, are exempt.

Who’s actually required to file Form 3520-A?

The trust files it and the trustee signs it, and the enforcement sits on the US owner. If you’re treated as the owner of any portion of a foreign trust under the grantor trust rules, the statute makes you responsible for seeing that the trust does its part, and IRC 6677(b)(1) makes you personally liable for the penalty when it doesn’t. Scope comes first, though. The instructions exempt certain Canadian plans, RRSPs and RRIFs among them, and certain eligible individuals’ tax-favored foreign trusts that pass an exclusivity test. Check that list before you diarise a date.

“such person shall submit such information as the Secretary may prescribe with respect to such trust for such year and shall be responsible to ensure that” the trust files the required return and furnishes the required statements IRC 6048(b)(1)

That responsibility is the whole design of this form. A foreign trustee with no US connection has little reason to file an IRS return, and the Code’s answer isn’t to chase the trustee. It’s to put the consequence on the US owner, and the penalty section says so in terms.

“the United States person referred to in such section shall be liable for the penalty imposed by subsection (a)” IRC 6677(b)(1), for a return required under section 6048(b)

The instructions are equally direct about signatures. Form 3520-A “must be signed by the trustee of the foreign trust”, and “a substitute Form 3520-A must be signed by the U.S. owner”. None of that reaches an account the instructions take out of foreign trust reporting altogether, and certain Canadian plans, RRSPs and RRIFs among them, are out of it.

“Rev. Proc. 2014-55 exempts from foreign trust information reporting certain Canadian retirement plans, including Canadian registered retirement savings plans (RRSPs) and Canadian registered retirement income funds (RRIFs).” Instructions for Form 3520-A, Exceptions To Filing

Rev. Proc. 2020-17 and the proposed regulations under section 6048 do the same for a second class, and the instructions describe the two in identical words: certain eligible individuals’ transactions with, and ownership of, certain tax-favored foreign trusts “established and operated exclusively or almost exclusively to provide pension or retirement benefits, or to provide medical, disability, or educational benefits”. Two parts of that sentence carry the weight. The exclusivity wording is the test itself rather than scene-setting, and “almost exclusively” is the only slack in it. And the “or” in the middle marks two alternative categories rather than one list of interchangeable purposes: Rev. Proc. 2020-17 defines a tax-favored foreign retirement trust at section 5.03 and a tax-favored foreign non-retirement savings trust at section 5.04, each with its own numbered requirements, so a trust has to fit one of them whole rather than borrow from both. Neither exemption reaches the FBAR or any other US reporting provision, which the instructions state expressly. So if your account is an RRSP or a RRIF, the deadline below may not be yours at all, and that is worth settling before anything else on this page.

When is it due and why so early?

The trust’s year end drives it rather than yours. The instructions to Form 3520-A put the trust’s return on “the 15th day of the 3rd month after the end of the foreign trust’s tax year”, so a calendar-year trust is on 15 March. Your own Form 3520 runs on a separate rule from your income tax return’s: the 15th day of the 4th month after your tax year ends, so 15 April for a calendar-year filer, the 6th month if you live and work, or are on military or naval duty, outside the US and Puerto Rico, claimed on a statement with the form, and the 10th month if your income tax return is extended.

“Form 3520-A is due by the 15th day of the 3rd month after the end of the foreign trust’s tax year. However, a substitute Form 3520-A attached to a U.S owner’s Form 3520 is due the same day as Form 3520.” Instructions for Form 3520-A, Reminders

“In general, a U.S person’s Form 3520 is due on the 15th day of the 4th month following the end of such person’s tax year for income tax purposes. For a calendar-year individual, this is generally the same day as the filer’s income tax return due date. If a U.S. person is granted an extension of time to file an income tax return, Form 3520 is due no later than the 15th day of the 10th month following the end of the U.S. person’s tax year. Note: This may differ from and is not tied to the due date of the U.S. person’s income tax return.” Instructions for Form 3520 (Rev. 12-2025), on when to file

Read that Note twice, because it is the opposite of how this usually gets explained. Your Form 3520 date coincides with your income tax return date when you are a calendar-year individual who has not extended. It does not derive from it. The 15 June branch is the one that catches cross-border readers: the same instructions say “taxpayers who live and work outside the United States have until the 15th day of the 6th month to file the form”, and test the condition “on the due date of your income tax return”. Two details of that test get missed. There are two qualifying limbs: living outside the United States and Puerto Rico with a place of business or post of duty outside the United States and Puerto Rico, or being in the military or naval service on duty outside the United States and Puerto Rico. And the branch has to be claimed on a statement filed with the form. So against a calendar-year trust’s 15 March, a calendar-year filer’s own date sits later on whichever branch applies, and the trust’s date moves with none of them.

Which filing	Due	Who signs it
The trust’s own Form 3520-A	15th day of the 3rd month after the trust’s year end	The trustee of the foreign trust
A substitute Form 3520-A	The same day as the US owner’s Form 3520	The US owner
The US owner’s own Form 3520	15th day of the 4th month after the owner’s tax year ends, the 6th month if the owner lives and works, or is on military or naval duty, outside the US and Puerto Rico and claims it on a statement with the form, the 10th month if the owner’s income tax return is extended	The US owner, as the individual filer

The trust’s own extension is a separate filing and it gets its own section below: Form 7004, lodged using the trust’s employer identification number, by the 15th day of the 3rd month after the trust’s year end.

What happens if the foreign trust never files it?

You file a substitute yourself, and doing so is what protects you from the penalty for the trust’s failure. The instructions set this out as an obligation rather than an option, and they attach it to your Form 3520. The substitute carries the owner statement and the beneficiary statement that form the back pages of the form, and copies of both have to reach the US owners and US beneficiaries they name by the Form 3520 due date. One caution from the instructions: only a complete Form 3520-A counts as timely, so a rushed shell lodged on time buys less than you think.

“If a foreign trust fails to file Form 3520-A, the U.S. owner must complete and attach a substitute Form 3520-A for the foreign trust to the U.S. owner’s Form 3520 … to avoid being subject to the penalty for the foreign trust’s failure to file a Form 3520-A.” Instructions for Form 3520-A

The deadline point is stated explicitly in the instructions and it’s the part worth reading twice. The substitute goes in “by the due date of the U.S. owner’s Form 3520 (and not the due date for Form 3520-A)”. The instructions then give the worked case themselves: a substitute completed to the best of the owner’s ability and attached to the Form 3520 by its due date, “such as April 15 for the U.S. owners who are individuals”, is considered timely filed. Read that April date as their example for a calendar-year individual who has not extended. It is not a fixed wall. The Form 3520 instructions put the substitute on “the due date of your Form 3520”, so it travels with whichever branch of that date applies to you, including the 15 June and 15 October ones.

Does my personal extension cover it?

Partly, and the split is the second trap. Your income tax extension does nothing for the trust’s own Form 3520-A. That one needs its own filing, Form 7004, lodged using the trust’s employer identification number rather than yours, by the 15th day of the 3rd month after the trust’s year end. It does move the substitute, though, because the substitute is due with your Form 3520 and an income tax extension carries Form 3520 to the 15th day of the 10th month, 15 October for a calendar-year filer.

“An extension of time to file an income tax return does NOT extend the time to file Form 3520-A. You MUST file Form 7004 using the foreign trust’s EIN to request an extension of time to file Form 3520-A.” Instructions for Form 3520-A, When To File

Note what that requires in practice. The trust needs an EIN before you can extend its return, so a trust that has never interacted with the IRS has a prerequisite step before the extension is even available. That is a reason to work out early which route you are on. The Form 7004 route closes on the trust’s own date, 15 March for a calendar-year trust, and the substitute route stays open on your own date, wherever that falls.

What’s the penalty if nobody files?

It lands on the US owner. IRC 6677(a) sets a penalty of “the greater of $10,000 or 35 percent of the gross reportable amount”, and Form 3520-A sits under the annual-return rules in section 6048(b), for which IRC 6677(b) makes the US person liable and applies subsection (a) “by substituting ‘5 percent’ for ‘35 percent’”. IRC 6677(d) blocks the penalty where the failure is shown to be due to reasonable cause and not willful neglect, but the instructions say a foreign fiduciary’s reluctance to hand over the required information is not reasonable cause.

• Whether a TFSA is a foreign trust at all, which is the prior question for many Canadians
• What TFSA reporting actually costs on a US return
• Fighting a Form 3520 penalty after the letter arrives

So the exposure on a 3520-A failure is the greater of $10,000 or 5 percent of the gross reportable amount, not 35 percent, and it applies unless the failure is shown to be due to reasonable cause and not willful neglect. Two things narrow that defence and both sit in the same instructions. A foreign fiduciary’s reluctance to hand over the required information is not reasonable cause, which is this page’s entire scenario. And where the failure runs on more than 90 days after the IRS mails a notice of failure to comply, section 6677(a) adds $10,000 for each 30-day period it continues.

That escalation is not open-ended, though, and the ceiling sits in the very next sentence of the same subsection. Once the IRS can determine the gross reportable amount, the later penalties are “reduced as necessary to assure that the aggregate amount of such penalties do not exceed the gross reportable amount”, with any excess already collected refunded to the taxpayer. The instructions carry the same cap in their own words. The gross reportable amount for this kind of failure is the gross value of the portion of the trust’s assets treated as owned by the US person at the close of the year, so the cap is the value of the owned portion rather than a number that keeps climbing, and the $10,000 floor still means a small trust can generate a penalty far larger than any tax at stake.

What should I do next?

Start with scope, because certain Canadian plans and certain eligible individuals’ tax-favored foreign trusts are exempt from this reporting altogether. If yours isn’t one, find the trust’s tax year end, since the trust’s own deadline counts from that rather than from your filing date, then work out which branch of your own Form 3520 date you’re in. Then ask one question of the trustee: have they filed Form 3520-A before, and will they this year. A clear no is more useful than a maybe, because it puts you on the substitute route early enough to prepare it properly.

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.