how do I report interest from Series I Savings Bond?

Did you get a 1099 INT from the bank for it?  You enter the interest as a 1099-INT and put the amount in box 3.

To enter Savings Bonds  just type Savings Bonds in the search box at the top of your return and click on the  Jump To link  at the top of the list.  Or

Enter Savings Bond interest like a 1099Int under

Federal Taxes tab

Wages & Income

Interest and Dividends

Interest on 1099INT - Click the Start or Update button

On the import screen scroll down and pick I'll enter it myself.

Type any description like Savings Bond  Interest

Savings Bond interest goes in box 3, not box 1.  You have to check the little box under box 1 that says my form has more boxes for it to open up.

If this was an electronic I bond, you can log in to your TreasuryDirect account and download the Form 1099-INT.  TreasuryDirect does not mail these Forms 1099-INT, they only provide them by download.

If this was a paper bond cashed at a bank, the bank is responsible for issuing the Form 1099-INT.

You can report the interest earned each year, or choose to wait until the 1099-INT is received.  Most people choose to wait until the 1099-INT is received.

Here's how to enter savings bond interest reported to you on a 1099-INT box 3 into TurboTax Online (You can follow these steps to report interest yearly if that is the option you choose.  Save your statements with your tax return information):

• Open TurboTax Online and navigate to Wages & Income > Investments and Savings (1099-B, 1099-INT, 1099-DIV, 1099-K, Crypto) > Add/Edit
• Under "Let's import", choose "Enter a different way." 
• Choose Interest, continue
• Choose "Type it in myself"
• Enter FEIN from payer, payer's name, and amount of interest. Choose recipient's name from dropdown box.
  • Under heading "Interest" there is a box for Box 3 - Interest on U.S. Savings Bonds and Treas. Obligations