The answer is: forever if you fail to file the tax return. But if you file the required returns and just can’t pay then the amount of time the IRS has to collect is limited by the IRS’s Collection Statute of Limitations.
The IRS Collection Statute Expiration Date (CSED) is the date after which the IRS can no longer collect a tax debt.
In general, the IRS has 10 years from the date of assessment to collect taxes owed. However, this 10 year period can be extended by certain actions of the taxpayer. These actions include: the submission and processing of an offer in compromise, bankruptcy proceedings, and the agreement of the taxpayer to extend the period for collections.
The IRS’s Collections Statute Expiration Date (CSED) is the date after which the IRS can no longer collect a tax debt. When things are simple, the CSED is easily calculated as 10 years from the date of assessment.
This CSED date is important to know when you have unpaid tax assessments. It tells you the amount of time remaining that the IRS has to collect on those assessments.
It’s important to discuss your options with your tax advisor.