The statute of limitations doesn't start until the tax return is filed.
If the taxpayer doesn't file, they give the IRS as long as the IRS
chooses to deal with the taxpayer and the missing return. Does this
taxpayer keep all his supporting documentation for his tax returns forever?
If the taxpayer did make an error and overpaid taxes for the tax year in
question, that refund will be lost if the return is filed more than 3
years after the original due date
Estimated taxes and/or withholdings would have generated a credit
balance at the IRS for that tax year. Eventually, they will send out a
CP80 notice informing them about the credit balance and asking for the
tax return to be filed. If they also ignore this, the credits will
eventually be forfeited. If the IRS ever digs itself out of the current
backlogs, they may finally get around to filing a substitute 1040 for
the tax year after the credits were automatically forfeited. That
computer generated letter may well demand the taxpayer pay the tax
again, plus the failure to file penalty, plus the failure to pay penalty
and years worth of interest. With a considerable amount of time and
possibly some expensive professional help the taxpayer may or may not be
able to reduce or eliminate the bill. To me, this scenario seems
unlikely but it appears to be a totally avoidable risk.
To me, not filing the return seems simply dumb.