Currently Not Collectible - CNC
In some situations, it is possible for the IRS to stop collections and put your debt on hold. You need to be current with all tax payments and compliant with all filings, but temporarily unable to pay a back-tax liability. In such as situation, the IRS may classify the debt as uncollectible.
The IRS essentially puts you in the filing cabinet but will check in from time to time. The debt remains – as do penalties and interest, which keep growing – but the IRS agrees to refrain from collection activities for a set period of time.