The extension is the most useful form in the business calendar and the most misread. Owners hear "six more months" and stop thinking about April. The IRS hears "six more months to file" and keeps charging interest from April on anything unpaid.
What it does
Form 7004, filed by the original due date, automatically extends the filing deadline: March 16 becomes September 15 for 1120-S and 1065 returns; April 15 becomes October 15 for Form 1120 and for the pro forma 1120 that carries Form 5472. No reason is required and it is not refused. Individuals use Form 4868 for the same effect on the 1040.
What it does not do
- It does not extend payment. Tax expected to be owed should be paid with the extension. Otherwise the failure-to-pay penalty (0.5% a month) and interest run from the original date. The failure-to-file penalty is avoided, which is the expensive one, so an extension without payment is still much better than nothing.
- It does not move estimated tax dates. April 15, June 15, September 15 and January 15 stay put.
- It does not move state annual reports or franchise tax dates, which are on the state's own calendar.
- It does not extend K-1s in any practical sense: partners still need them, so an extended partnership usually means extended partners.
Why foreign-owned LLCs should file one every year
A foreign-owned single-member LLC usually owes no tax with its pro forma 1120, so the payment question does not arise. The extension still matters because it moves the Form 5472 deadline, and the penalty for missing that is $25,000. Filing Form 7004 by April 15 costs nothing and buys six months. We file it by default for every non-resident client whose books are not closed by March.
How to estimate the payment
Use last year's tax as a floor, adjust for what you know about this year, and round up. Overpayment comes back as a refund or a credit against next year's estimates; underpayment costs about 7% a year plus half a percent a month. When the books are current, the estimate takes an hour. When they are not, the extension buys the time to make them current, which is its real purpose.
The mistakes that cost money
- Filing the extension on April 16. A late extension is not an extension.
- Extending the entity and forgetting the owners' personal returns, or the reverse.
- Assuming the state accepted the federal extension. Many do automatically; some want their own form or a payment.
- Extending every year as a habit and doing nothing in the extra six months. October arrives with the same missing books.
The check: if you filed an extension last year, look at whether any tax was paid with it. If not, and tax was due, the interest and payment penalty are already on the account.