We cashed in all my husband's savings bonds before he died. He had like 200 of them. Took the bank 2 days to enter them all in. I use Quicken and a spreadsheet. You only enter the interest and pay tax on it. I got a 1099INT from the bank to report the interest, I wasn't expecting to get a 1099 Int. The total Value cashed in - the interest should equal your cost basis. You actually don't need the cost basis unless it's different than the bank used. I had been keeping track of them the whole time using the Treasury Savings Bond Wizard but they discontinued it and I had to switch to the online Treasury Direct Savings Bond Calculator. You can list them all and update it when you want. The bank interest matched my interest.
Was there a lot of interest? The interest will add to your total income for the year and may push you into a higher tax bracket so you may want to send in an Estimated payment. I was already making estimated payments for other things so I just increased my estimated payments. There shouldn't be any state tax on the interest. If you don't get a 1099-Int from the bank then you will enter the interest like a 1099 Int and put the amount in box 3 (not box 1).
