Normally, the IRS has 3 years after the due date of the date you filed it to initiate an audit, so it is important and it's your duty to keep your tax returns and supporting documents for at least 3 years before shredding them. There are some exceptions though, as some types of documents need to be kept for more or less than the “3-Year Rule.” There are 3 main milestones for how long you should keep old tax records before shredding: 1 year, 3 years, and 6 years.
Different types of information used for your taxes need to be kept after filing for both security and legal compliance. It’s important you’re able to provide all the documents you used to file, as the IRS has up to 6 years to audit tax returns.
If you fail to report 25% or more of gross income (not recommended):