Most US federal returns for the 2025 tax year were due on 15 April 2026. Partnership and S corporation returns were due on 16 March 2026, because 15 March fell on a Sunday. As of 17 September 2026, every original deadline for a calendar-year 2025 return has passed, and so has the extended 15 September date for Forms 1065 and 1120-S. The next big date is Thursday 15 October 2026: the extended deadline for Forms 1040, 1040-NR, 1120, and the pro forma 1120 with Form 5472 that foreign-owned single-member LLCs file.
This guide gives every 2026 deadline with the IRS source linked (all checked September 2026). It shows which return your LLC files based on how it’s taxed, and what non-resident owners must file. It also covers extensions, the penalties for missing a date, and what’s already known about the 2027 filing season.
In this guide: 2026 deadline table · What’s still ahead · Which return your LLC files · Form 5472 for foreign-owned LLCs · Form 1040-NR · Extensions · Penalties · BOI reports · State annual reports · Who must file · The 2027 filing season · FAQ
Key US tax filing deadlines for the 2025 tax year (filed in 2026)
These dates are for calendar-year filers, which covers almost every small LLC. When a due date falls on a Saturday, Sunday or legal holiday, the IRS treats a return filed on the next business day as on time (IRS Publication 509, Tax Calendars for 2026).
| Return | Who files it | Original due date | Extended due date | Status on 17 September 2026 |
|---|---|---|---|---|
| Form 1065 | Multi-member LLCs taxed as partnerships | Monday 16 March 2026 | Tuesday 15 September 2026 | Both dates passed |
| Form 1120-S | LLCs and corporations taxed as S corporations | Monday 16 March 2026 | Tuesday 15 September 2026 | Both dates passed |
| Form 1040 | US citizens and residents, including single-member LLC owners who file Schedule C | Wednesday 15 April 2026 | Thursday 15 October 2026 | Extended date still ahead |
| Form 1120 | C corporations, including LLCs that elected corporate tax treatment | Wednesday 15 April 2026 | Thursday 15 October 2026 | Extended date still ahead |
| Pro forma Form 1120 + Form 5472 | Single-member LLCs owned by a foreign person | Wednesday 15 April 2026 | Thursday 15 October 2026 | Extended date still ahead |
| Form 1040-NR (you received wages as an employee subject to US income tax withholding) | Non-resident individuals | Wednesday 15 April 2026 | Thursday 15 October 2026 | Extended date still ahead |
| Form 1040-NR (neither of the above) | Non-resident individuals | Monday 15 June 2026 | Tuesday 15 December 2026 (six months later; see below) | Extended date still ahead |
Sources: the March, April, September and October 2026 entries in Publication 509 (2026); the 2025 Form 1120-S instructions (“the due date is March 16, 2026 (March 15th falls on Sunday)”); the 2025 Form 1040-NR instructions and the IRS page on taxation of nonresident aliens; and the Form 5472 instructions, which tie the pro forma 1120 to Form 1120’s due date, including extensions.
An extended date only applies if an extension was filed by the original due date. If you didn’t file Form 4868 or Form 7004 by then, your return is already late. File it as soon as you can, because some penalties grow every month (see penalties).
Fiscal-year companies follow the same “15th day of the Nth month” rules, counted from their own year-end. A C corporation whose year ends on 30 June files by the 15th day of the 3rd month instead of the 4th (2025 Form 1120 instructions).
The IRS also postpones deadlines for taxpayers in federally declared disaster areas. If your LLC’s address is in one, check the IRS disaster relief page before you assume a date has passed.
What’s still ahead in 2026 (as of 17 September)
- Thursday 15 October 2026: the last day to file an extended 2025 Form 1040, Form 1040-NR (April filers), Form 1120, or pro forma Form 1120 with Form 5472. The IRS generally can’t extend a return by more than six months, so there is no second extension to ask for (Form 4868, 2025).
- Tuesday 15 December 2026: the extended date for a Form 1040-NR whose original due date was 15 June 2026. That’s six months after 15 June, the most Form 4868 allows. We didn’t find an IRS page that prints this date, so ask your preparer to confirm it before you rely on it.
- Already late? If a return was due on 16 March, 15 April or 15 June and you filed no extension, or the extended 15 September date has now passed for a 1065 or 1120-S, file as soon as you can. Partnership and S corporation penalties are charged per owner for each month, for up to 12 months, even when no tax is owed (see penalties).
Which return your LLC files, and when
There’s no single “LLC tax return.” The IRS taxes an LLC according to its classification, and the classification decides both the form and the deadline. By default, an LLC with one member is “disregarded as separate from its owner,” and a US LLC with two or more members is a partnership. An LLC can file Form 8832 to be taxed as a corporation instead (IRS: Limited Liability Company).
| How the LLC is taxed | Federal return | 2025 return due |
|---|---|---|
| Single member who is a US person (disregarded entity) | No separate LLC return. The owner reports the business on Schedule C with Form 1040 | 15 April 2026 |
| Single member who is a foreign person (disregarded entity) | Pro forma Form 1120 with Form 5472 attached, plus the owner’s own Form 1040-NR if the owner has to file one | 15 April 2026 (1040-NR: 15 April or 15 June) |
| Two or more members (partnership) | Form 1065, plus a Schedule K-1 for each member | 16 March 2026 |
| Elected S corporation | Form 1120-S, plus K-1s | 16 March 2026 |
| Elected C corporation | Form 1120 (with Form 5472 if at least 25% foreign-owned) | 15 April 2026 |
Single-member LLC owned by a US person
The LLC doesn’t file its own income tax return. Its income and expenses go on the owner’s Schedule C, which is filed with Form 1040 by 15 April. Self-employment tax applies once net earnings from self-employment reach $400 (2025 Form 1040 instructions). A single-member LLC is still a separate entity for employment and certain excise taxes, so an LLC with employees has payroll filings of its own (IRS).
Single-member LLC owned by a non-US person
This is the setup most Bizstartz clients have, and it has its own rules. The LLC is still disregarded for income tax, but it’s treated as a US corporation for one purpose: reporting transactions with its foreign owner. It files a pro forma Form 1120 with Form 5472 by 15 April. The next section covers it in full.
Multi-member LLC (partnership)
The LLC files Form 1065, an information return, and gives each member a Schedule K-1 showing their share of income, deductions and credits. The members pay any tax on their own returns. The 2025 return was due 16 March 2026, or 15 September 2026 with Form 7004. A partnership has to file unless it “neither receives income nor incurs any expenditures treated as deductions or credits,” so a quiet year with a few expenses still needs a return (2025 Form 1065 instructions).
LLC taxed as an S corporation
An LLC that elects S corporation status files Form 1120-S on the same schedule as a partnership: 16 March 2026, or 15 September 2026 with an extension. The election on Form 2553 must be filed “no more than 2 months and 15 days after the beginning of the tax year the election is to take effect” (2025 Form 1120-S instructions).
If you live outside the US, this option isn’t open to you. An S corporation can’t have non-resident alien shareholders (IRS: S corporations). If a guide suggests an S corp election to a founder abroad, it’s wrong.
LLC taxed as a C corporation
The LLC files Form 1120 and pays corporate income tax itself. Owners are taxed again on dividends they receive. The 2025 return was due 15 April 2026, or 15 October 2026 with Form 7004. If a foreign person owns at least 25%, the company is a “reporting corporation” and attaches Form 5472 as well (Form 5472 instructions).
Foreign-owned single-member LLC: Form 5472 and the pro forma Form 1120
If you live outside the US and own a US LLC by yourself, this is the deadline that matters most. Everything in this section comes from the IRS Instructions for Form 5472 (Rev. 12/2024, checked September 2026).
What you file
- A pro forma Form 1120 with “Foreign-owned U.S. DE” written across the top. Only a few items are completed, including the company’s name and address.
- Form 5472 attached to it, reporting transactions between the LLC and its foreign owner or other related parties. You need a separate Form 5472 for each related party the LLC dealt with.
The return isn’t about tax owed, and the LLC files it even though it has no income tax return of its own. What triggers it is a “reportable transaction,” and for a foreign-owned LLC that includes amounts paid or received for the company’s “formation, dissolution, acquisition, and disposition,” including “contributions to, and distributions from, the entity.” Paying the formation costs, putting money into the LLC’s bank account, or taking money out all count. So a company with no sales can still have to file.
When it’s due
- Original due date: the due date of Form 1120, the 15th day of the 4th month after year-end. For 2025, that was Wednesday 15 April 2026.
- Extension: file Form 7004 by the original due date, using the Form 1120 code on Part I, line 1. That moves the filing date to Thursday 15 October 2026.
How to file it (it can’t be e-filed)
The instructions say plainly: “If you are a foreign-owned U.S. DE, you cannot file Form 5472 electronically.” You have two options:
- Fax at 300 DPI or higher to 855-887-7737, or
- Mail to Internal Revenue Service, 1973 Rulon White Blvd, M/S 6112, Attn: PIN Unit, Ogden, UT 84201.
Keep the fax confirmation or the courier’s proof of delivery. If the IRS ever says the return didn’t arrive, that record is what you have.
The penalty: $25,000
“A penalty of $25,000 will be assessed on any reporting corporation that fails to file Form 5472 when due and in the manner prescribed.” A “substantially incomplete” Form 5472 counts as not filing. If the failure continues for more than 90 days after the IRS notifies you, another $25,000 is added for each 30-day period it continues. That’s why a late or sloppy 5472 is the most expensive mistake on this page, even for a company that made no money.
For line-by-line help, see our guide to Form 5472 for foreign-owned US LLCs.
Form 1040-NR: your own return as a non-resident owner
Form 5472 is the LLC’s filing. Whether you also file a personal US return is a separate question, worked through step by step in our guide to Form 1040-NR. The IRS says a non-resident alien must file Form 1040-NR if they are “engaged or considered to be engaged in a trade or business in the United States during the year.” Filing may also be required if tax withheld didn’t cover what you owe, or if you want a refund of tax that was over-withheld (IRS: Taxation of nonresident aliens, updated 17 February 2026).
The 1040-NR instructions add that once you’re engaged in a US trade or business, you must file “even if” you have no income from that business, no US-source income, or income that a tax treaty exempts (2025 Form 1040-NR instructions). Many founders who sell services from abroad through a US LLC have no US trade or business. Others, such as those with US inventory, US staff or a US office, may. That judgement depends on your facts, so it’s worth settling with a US tax adviser once rather than guessing every year.
1040-NR due dates for 2025 returns
- 15 April 2026 if you received wages as an employee subject to US income tax withholding, or you have an office or place of business in the US.
- 15 June 2026 if neither applies.
- Extension: Form 4868, filed by the original due date. Form 4868 has a box on line 9 for 1040-NR filers whose return is due 15 June. The extension gives up to six months: 15 October 2026 for April filers, and by our calculation 15 December 2026 for June filers.
Don’t sit on a return you’re required to file. The IRS warns that deductions and credits can be denied on a non-resident return filed more than 16 months late (IRS). A 1040-NR also needs a taxpayer identification number; if you don’t have an SSN, that means an ITIN. Our guide to getting an ITIN as a foreigner explains the application.
Tax filing extensions: what they do and don’t do
| Form | Used for | Extra time | Deadline to request |
|---|---|---|---|
| Form 4868 | Forms 1040, 1040-SR, 1040-NR, 1040-SS | Up to 6 months | The return’s original due date |
| Form 7004 | Forms 1065, 1120-S, 1120, and the pro forma 1120 with Form 5472 | 6 months for most returns (7 months for C corporations with a 30 June year-end starting before 1 January 2026) | The return’s original due date |
Rules that catch people out:
- An extension is for filing, not paying. “Form 7004 does not extend the time to pay any tax due” (Form 7004 instructions, Rev. 12/2025). The same applies to Form 4868. Interest and the late-payment penalty run from the original due date on anything unpaid.
- It must be filed on time. A Form 7004 sent after the original due date doesn’t create an extension.
- It’s automatic. You don’t need to give a reason, and the IRS doesn’t send an approval.
- Six months is the limit. There’s no further extension after 15 October 2026 for April returns.
US citizens and resident aliens who live outside the US on the due date get an automatic two extra months, to 15 June 2026, to file and pay (Form 4868). That rule is for US citizens and residents abroad. It doesn’t apply to a non-resident’s 1040-NR or to an LLC’s return.
Penalties for late filing or late payment
What you pay for a missed deadline depends on the return. Figures are for returns required to be filed in 2026 (checked September 2026).
| Return | Late filing penalty | Source |
|---|---|---|
| Form 1040 / 1040-NR (and Schedule C for a single-member LLC) | 5% of unpaid tax for each month or part of a month late, up to 25%. If more than 60 days late, at least $525 or the tax due, whichever is smaller | IRS: Failure to file penalty |
| Form 1065 (multi-member LLC) | $255 per partner for each month or part of a month late, for up to 12 months. Charged even when no tax is due. Also up to $340 for each Schedule K-1 not furnished correctly or on time | 2025 Form 1065 instructions |
| Form 1120-S (S corporation) | $255 per shareholder for each month or part of a month late, for up to 12 months, plus penalties on any tax due | 2025 Form 1120-S instructions |
| Form 1120 (C corporation) | 5% of unpaid tax per month, up to 25%. If more than 60 days late, at least $525 or the tax due, whichever is smaller | 2025 Form 1120 instructions |
| Pro forma 1120 + Form 5472 (foreign-owned LLC) | $25,000, plus $25,000 for each 30-day period the failure continues beyond 90 days after IRS notice | Form 5472 instructions |
On top of late filing:
- Failure to pay: 0.5% of unpaid tax for each month or part of a month, up to 25%. It drops to 0.25% a month while an approved payment plan is in place, and rises to 1% a month if you don’t pay within 10 days of a notice of intent to levy (IRS: Failure to pay penalty).
- Both at once: when both penalties apply in the same month, the late-filing penalty is reduced by the late-payment penalty (IRS).
- Interest is charged on unpaid tax and penalties until they’re paid.
For an example: a two-member LLC that files its 2025 Form 1065 four months late, with no extension, faces 2 × $255 × 4 = $2,040, even if it owed no tax.
If you can’t pay in full, file on time anyway. The late-filing penalty is ten times the monthly late-payment rate, and a payment plan halves the payment rate.
BOI reports: no longer required for US-formed LLCs
Many 2024 and early 2025 guides, including earlier versions of this one, listed a FinCEN beneficial ownership information (BOI) report as an annual compliance task. That has changed.
- On 21 March 2025, FinCEN announced an interim final rule removing the BOI reporting requirement for US companies and US persons, published in the Federal Register on 26 March 2025 (Federal Register).
- On 11 August 2026, FinCEN issued a final rule that “permanently removes the requirement for U.S. companies and U.S. persons to report beneficial ownership information” (FinCEN news release).
FinCEN’s BOI page now says “U.S. companies are exempt.” A Wyoming, Delaware or New Mexico LLC formed in the US doesn’t file a BOI report, whoever owns it. The rule still applies to foreign entities registered to do business in the US; they have 30 calendar days after their registration takes effect to file. A company formed abroad, such as a UK Ltd registered in a US state, should check FinCEN’s page.
State annual reports and taxes: a separate set of deadlines
Everything above is federal. The state where your LLC is formed has its own annual filing, with its own due date and its own consequences, and the IRS deadlines don’t change it. Two common examples (checked September 2026):
- Wyoming: the annual report is due on the first day of the LLC’s anniversary month. An LLC formed on 15 May files by 1 May each year (Wyoming Secretary of State). The license tax is $60 or two-tenths of a mill on Wyoming assets, whichever is greater (fee schedule effective 1 July 2026). More in our Wyoming LLC annual filing guide.
- Delaware: LLCs don’t file an annual report but pay an annual tax on or before 1 June. The Division of Corporations currently lists the tax as $400, with a $200 penalty plus 1.5% interest a month if it’s late (Delaware Division of Corporations). Delaware raised the tax from $300 in 2026, so check the page before you pay.
Other states differ, and some also levy state income or franchise taxes. If you don’t want to track the date yourself, our annual compliance filing service watches state deadlines for you.
Who is required to file a US tax return?
US citizens and residents generally file Form 1040 when gross income passes a threshold that depends on filing status and age. For 2025, the thresholds for filers under 65 were (2025 Form 1040 instructions, Chart A):
- Single: $15,750
- Married filing jointly (both under 65): $31,500
- Head of household: $23,625
- Self-employed, including single-member LLC owners: net earnings from self-employment of $400 or more, whatever your total income
Filing below the threshold can still be worth it to get back tax that was withheld or to claim refundable credits.
Non-residents don’t use those thresholds. “Most nonresident aliens and dual-status aliens have different filing requirements and may have to file Form 1040-NR” (IRS). See the 1040-NR section above. Separately, a foreign-owned single-member LLC files its pro forma 1120 and Form 5472 whether or not the owner files anything.
Tax forms for the 2025 tax year at a glance
Individual forms
- Form 1040: the main return for US citizens and residents
- Form 1040-NR: the return for non-resident aliens
- Schedule C: profit or loss from a sole proprietorship or single-member LLC owned by a US person
- Schedule SE: self-employment tax
- Form 4868: extension for individual returns
Business forms
- Form 1065: partnership return (multi-member LLCs)
- Schedule K-1: each owner’s share, issued by partnerships and S corporations
- Form 1120-S: S corporation return
- Form 1120: C corporation return, and the pro forma version foreign-owned single-member LLCs file
- Form 5472: information return for 25% foreign-owned corporations and foreign-owned disregarded entities
- Form 7004: extension for business returns
- Forms 8832 and 2553: elections to be taxed as a corporation or S corporation
Looking ahead: the 2027 filing season (tax year 2026)
The IRS publishes its 2027 tax calendar near the end of 2026, and it hasn’t announced when the 2027 filing season opens. (The 2026 season opened on Monday 26 January 2026, per IRS news release IR-2026-02.) The rules that set the due dates haven’t changed, though, so for calendar-year 2026 returns they work out as follows. None of these dates falls on a weekend.
| Return (tax year 2026) | Due date | With extension |
|---|---|---|
| Form 1065, Form 1120-S | Monday 15 March 2027 | Wednesday 15 September 2027 |
| Form 1040, Form 1120, pro forma 1120 + Form 5472, Form 1040-NR (April filers) | Thursday 15 April 2027 | Friday 15 October 2027 |
| Form 1040-NR (no wages subject to US withholding) | Tuesday 15 June 2027 | Wednesday 15 December 2027 |
These are calculated from the “15th day of the 3rd, 4th or 6th month” rules in Publication 509 and the form instructions. Check them against Publication 509 for 2027 when it’s out, especially if your state has a disaster declaration.
How to prepare for your next deadline
Late returns usually come from records that aren’t ready, not from forgetting the date. Before your preparer starts, have:
- The LLC’s formation documents and EIN letter, and your ITIN if you have one.
- A full year of bank and payment-platform statements (Mercury, Wise, Stripe, PayPal and so on).
- A list of every transfer between you and the LLC: money you put in, money you took out, and anything the LLC paid for you or you paid for it. For a foreign-owned LLC, this is what goes on Form 5472.
- A profit and loss summary, with receipts for the expenses on it.
- Last year’s returns and K-1s, and any IRS letters received since.
- For multi-member LLCs: each member’s name, address, tax ID and ownership percentage.
Put the original due date and the extension date in your calendar now. If your preparer is busy in March and April, ask them to file Form 7004 or 4868 early rather than on the last day.
How Bizstartz can help
Bizstartz works with founders who live outside the US and own US LLCs. Our US tax filing service covers preparing the federal return (the pro forma 1120 and Form 5472, or Form 1120, as applicable), state tax filings where required, a review for treaty benefits, and filing before the deadline. If your 2025 return is on extension, the deadline for most of these is 15 October 2026, so get in touch well before then.
We prepare and file on your behalf. Whether penalties are charged or waived, and how long processing takes, are decided by the IRS.
Frequently asked questions
What was the US tax filing deadline for 2025 income?
For most individuals and C corporations, 15 April 2026. Partnerships (Form 1065) and S corporations (Form 1120-S) were due 16 March 2026, because 15 March was a Sunday. Non-residents who received no wages subject to US income tax withholding had until 15 June 2026 for Form 1040-NR. The “office in the United States” test in the instructions applies to non-resident estates and trusts, not to individuals.
Can I still file my 2025 return on extension?
Only if you filed Form 4868 or Form 7004 by the original due date. Then Forms 1040, 1040-NR (April filers), 1120 and the pro forma 1120 with Form 5472 are due by 15 October 2026. The extended date for Forms 1065 and 1120-S was 15 September 2026, which has passed. An extension never extends the time to pay tax.
When is Form 5472 due for a foreign-owned LLC?
With the pro forma Form 1120, by the 15th day of the 4th month after the LLC’s tax year ends. For 2025 that was 15 April 2026, or 15 October 2026 with Form 7004. It can’t be e-filed. You fax it to 855-887-7737 or mail it to the IRS in Ogden, Utah. The penalty for not filing is $25,000.
What is the tax filing deadline for an LLC?
It depends on how the LLC is taxed. A multi-member LLC (partnership) or an LLC taxed as an S corporation files by 15 March, or the next business day. A single-member LLC owned by a US person reports on the owner’s Form 1040 by 15 April. A single-member LLC owned by a foreign person files a pro forma Form 1120 with Form 5472 by 15 April. An LLC taxed as a C corporation files Form 1120 by 15 April.
What happens if I miss the tax filing deadline?
Penalties start straight away. Individual and C corporation returns pay 5% of unpaid tax a month, up to 25%, with a minimum of $525 or the tax due, whichever is smaller, once 60 days late. Partnerships and S corporations pay $255 per owner per month for up to 12 months, even with no tax due. A foreign-owned LLC that misses Form 5472 faces $25,000. Interest and late-payment penalties add to all of these, so file as soon as you can.
Do non-US residents with a US LLC need to file US taxes?
The LLC usually does. A single-member LLC owned by a foreign person files a pro forma Form 1120 with Form 5472 for any year with a reportable transaction, and money moving between you and the company counts, even without sales. Whether you also file Form 1040-NR depends on whether you’re engaged in a US trade or business or have US income that withholding didn’t cover.
Do I still need to file a BOI report for my LLC?
Not for an LLC formed in the US. FinCEN’s final rule of 11 August 2026 permanently removed BOI reporting for US companies and US persons. Foreign entities registered to do business in a US state are still covered.
This guide was updated with the help of AI tools. Every deadline, fee and penalty links to the IRS, FinCEN or state page it came from, and those sources were checked on 17 September 2026. Where a date is calculated rather than published, the text says so. It’s general information, not tax advice for your situation.
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