Failure to file tax returns can be classified as tax fraud by the IRS. While that term does manage to make it sound much more serious, failure to file by itself doesn’t often result in jail time. Still it’s not impossible—just ask Wesley Snipes! Usually though, the government wants taxpayers earning money so it can collect those taxes. Sending non-payers to prison isn’t going to facilitate that.
The federal or California state government would have to be convinced that your failure to file taxes was intentional before considering something as severe as a jail term. Failure to file over many years, coupled with other bad conduct such as hiding assets, for example, could be subject to criminal penalties including imprisonment and/or fines. In lesser cases, you are more likely going to be liable for back taxes and civil penalties, plus interest.
Failure to File Tax Returns and Failure to Pay