Neither the bank nor IRS keeps records beyond 7 years. The IRS will have the 1040 summary for a few years beyond that, but not any detail, i.e., how much was earned in interest beyond the 7 years.
If they suspect you of tax fraud, the IRS can go back on you 10 years, and they will have the records to do it.
//Neither the bank nor IRS keeps records beyond 7 years.//
NOT TRUE. I know for a fact that the IRS keeps records longer (we have had them come back with tax issues over 20 years later) and my bank and several others have records for over 50 years - they just keep them in storage and don’t like to bother to look. They will amazingly have the records if something goes to court.
The 7 year thing is a myth in a lot of areas. ALWAYS keep your records forever.