The statute of limitations on unfiled taxes is essentially infinite, but the window to audit a return is only six years, so if you just file a 1040 with a zero on it every year and 20 years from now the IRS decides to get frisky, you're covered for all but the last 6 years automatically.
This is not technically correct. There are three time limits that apply:
In a normal circumstances, they have 3 years to conduct an audit.
If they suspect you've under-reported your income by 25% or more they have 6 years.
If they suspect fraud, they have unlimited time to conduct an audit. (Fraud requires intent to deceive, so it's a higher bar than just making a mistake or not understanding a rule.)
This is not technically correct. There are three time limits that apply:
In a normal circumstances, they have 3 years to conduct an audit.
If they suspect you've under-reported your income by 25% or more they have 6 years.
If they suspect fraud, they have unlimited time to conduct an audit. (Fraud requires intent to deceive, so it's a higher bar than just making a mistake or not understanding a rule.)