Can I get an extension?

Extensions to file are generally available for most returns. An extension to file is not an extension to pay — interest and penalties accrue on tax unpaid by the original due date even where the return is filed later on a valid extension.

What if I miss a deadline?

Penalties differ by form. Income tax returns generally accrue a percentage of unpaid tax per month. Information returns such as Form 5472 carry flat penalties regardless of tax owed. First-time penalty abatement exists for some taxpayers with a clean compliance history — it is worth asking for.

Do state deadlines match federal ones?

Often but not always, and state annual reports and franchise taxes run on entirely separate calendars — Delaware's LLC franchise tax is due 1 June, for example. Track state and federal obligations separately.

US business taxes: every form, deadline and obligation

Guide · 1 min read

US business tax deadlines: what is due and when

Different entities, different dates. The one that catches foreign owners is not the one they expect.

The short answer

US partnership and S-Corporation returns are generally due 15 March. C-Corporation returns, foreign-owned single-member LLC filings on Form 5472, and individual returns are generally due 15 April. Dates shift for weekends, holidays and fiscal-year filers, so confirm against the IRS calendar each year.

Return	Who files	Typical due date
Form 1065	Multi-member LLCs and partnerships	15 March
Form 1120-S	S-Corporations	15 March
Form 1120	C-Corporations	15 April
Form 5472 + pro forma 1120	Foreign-owned single-member LLCs	15 April
Form 1040 / Schedule C	US individual owners	15 April
Form 1040-NR	Non-residents with a US filing need	15 April or 15 June, depending on facts
Estimated tax	Owners with a US liability	Quarterly

Dates shift for weekends, holidays, disaster relief and fiscal-year filers. Confirm against the IRS calendar each year.

Partnership returns come first for a reason

The 15 March partnership deadline sits before the individual deadline deliberately: partners need their Schedule K-1 before they can complete their own returns. A late partnership return therefore delays every partner, and the penalty is charged per partner per month.

State-level obligations run separately — see compliance for annual reports and franchise tax.

Frequently asked questions

Can I get an extension?: Extensions to file are generally available for most returns. An extension to file is not an extension to pay — interest and penalties accrue on tax unpaid by the original due date even where the return is filed later on a valid extension.
What if I miss a deadline?: Penalties differ by form. Income tax returns generally accrue a percentage of unpaid tax per month. Information returns such as Form 5472 carry flat penalties regardless of tax owed. First-time penalty abatement exists for some taxpayers with a clean compliance history — it is worth asking for.
Do state deadlines match federal ones?: Often but not always, and state annual reports and franchise taxes run on entirely separate calendars — Delaware's LLC franchise tax is due 1 June, for example. Track state and federal obligations separately.

Sources

Last reviewed August 23, 2026. Verify against the primary source before acting.

Founders 8 does not provide tax advice. Tax residency depends on facts and rules specific to each jurisdiction — review your position with a qualified adviser.

More in US business taxes: every form, deadline and obligation

All of US business taxes: every form, deadline and obligation