The tax code sets out time limits, or statutes of limitations for the IRS to pursue non-filers.
Criminal – The IRS can only bring criminal charges against a non-filer within 6 years of the due date of the return.
Civil – There is no deadline, however, on the IRS going after non-filers and imposing civil penalties, in addition to taxes owed. This means that while you can’t be put in jail for not filing a 1988 tax return, you will forever owe the IRS a return as long as you have earned enough to have had an obligation to file. Also, you will be fined with penalties and be required to pay interest on the unfiled returns forever. The IRS may file an SFR (substitute for return) on your behalf based upon the data they have which is never a favorable situation for a taxpayer.