The Rule
IRC Section 6502 gives the IRS ten years from assessment to collect. After the CSED passes, the debt is gone. The IRS cannot collect, the lien is released, and the balance drops to zero. This is not a technicality. It is black letter law.
What Extends the Clock
Filing bankruptcy tolls the CSED for the case plus six months. Submitting an OIC tolls it while pending plus 30 days. Signing Form 900 (a voluntary extension) adds whatever time you agreed to. Living outside the country for more than six months. These events can add years to the collection period.
Strategy
Before making any resolution move, calculate the remaining CSED for each tax year. An OIC that saves $30,000 but adds a year to a statute that would have expired in eight months is a bad trade. CNC status that lets the clock run without payments or statute extensions is sometimes the mathematically superior choice.
The CSED is the most powerful number in tax debt resolution. Every strategy should start with knowing that number for each year you owe.