The short answer
Generally 10 years from the date the tax is assessed. After that, the IRS can no longer collect it. Some events, like a pending offer or plan request, pause or extend the clock. Each tax year and each extra assessment has its own end date, called the CSED.
If you never filed, the clock can't start for that year until a tax is assessed.
Words to know
- Assessment
- When the IRS records a tax you owe on its books. The 10 year collection clock starts here.