State tax extensions

Every state with an income tax handles extensions one of three ways, and the way your state handles it determines whether your April 15 federal extension did anything for your state return.

Pattern one: the federal extension is honored

The state grants you the same six months if you have a valid federal extension and, in most of these states, owe nothing or have paid what you owe. Some ask you to attach a copy of Form 4868 to the state return. Some just want the box checked. Examples in this group have included New York for many years, though states move between groups, so verify each season.

Pattern two: the state wants its own request

A state form, filed by the state deadline, regardless of what you did federally. Filing federally and skipping the state form leaves the state return late from the original date.

Pattern three: the extension is conditional on payment

The state extends your filing date automatically, but only if you pay a threshold percentage of your final tax (often 80 to 100 percent) by the original due date. No payment, no extension, and the late filing penalty is computed from April.

Two things that are true everywhere

No state extends the payment. And the states with no income tax still have business filings with their own extension rules.

What to do

Look up your state's rule before April, not after. If the state has its own form, file it the same day you file the federal one. If the extension is conditional on payment, pay by the original date and keep the confirmation. The state extension request letter covers the few states that accept a written request.

Sources

1. Each state's department of revenue. Links are added to the state entries as they are published.
2. IRS, State government websites