2025 tax deadlines for non-US LLC owners

IRS already updated the 2025 tax deadlines for non-US LLC owners.
And they aren’t what you think.

Most founders are still working off 2024 calendars.

That’s a four-figure mistake waiting to happen…

Here are the dates that matter RIGHT NOW:

→ March 17, 2025: Form 1120 (if your LLC elected C-corp status)
→ April 15, 2025: Form 1040 (if you’re a U.S. tax resident with LLC income)
→ June 16, 2025: Form 1040-NR (for non-resident aliens)
→ June 16, 2025: Form 5472 + Pro-forma 1120 (Foreign-owned LLCs must file even with ZERO transactions)
→ September 15, 2025: Extended deadline (if you filed for extension)

Now, here’s what blindsides founders every year:

→ Your LLC formation date doesn’t determine your tax year
→ State tax deadlines are different from federal
→ Form 5472 has a separate deadline (with $25K penalty for late filing)
→ Extensions don’t extend your payment deadline

The most expensive assumption in this scenario is:
‘I’ll just file when my accountant tells me to.’

If your accountant doesn’t specialize in non-US LLC owners, they might not know about many forums, FinCEN BOI requirements, or state-specific nexus rules.

And you’re still liable.

So here’s what you need to do TODAY:

1. Mark every single deadline in your calendar
2. Set reminders 30 days before each date
3. Confirm which forms YOU specifically need to file
4. Don’t assume your situation matches someone else’s

The IRS doesn’t grade on effort.
They grade on dates.
And the penalties compound daily.