Why you should NEVER throw away your tax returns.
The IRS has it wrong. Here’s an excellent article explaining why you should never throw away your tax returns in accordance with the IRS guidelines.
After 6 years, it wouldn’t be necessary to keep copies of checks, bank statements, cash receipts, etc, but I would keep copies of all source documents, such as Forms W-2, 1099’s 1098’s etc. along with the copy of the return.