For I Bond interest we recommend that you rely on the Rate of Return. When you do this the Planner will model interest on a yearly basis that is taxable.
If you want more granularity, we generally recommend the following:
First, set up the I Bond account
STEP 1: Head over to MyPlan > Accounts and Assets
STEP 2: ➕ Add the account as a Checking/Savings/Investment account
STEP 3: Give the account a descriptive name, "I Bonds" for example
STEP 4: Select Ordinary Income as your tax treatment
STEP 5: Set your rates of return to 0%
STEP 6: Exclude the account from your withdrawal strategy
Next bring the interest income in as a lump sum pension
STEP 7: Head over to MyPlan > Income > Pensions
STEP 8: When asked “what type of pension is this?” select Lump Sum
STEP 9: Enter a descriptive name for the income, eg: "I Bond Interest”
STEP 10: Enter the value of the lump sum pension should be the future value of the interest you expect to receive at the bond's maturity date
STEP 11: Select the maturity date as the payment age
STEP 12: Select the "I Bond" account as the deposit account
STEP 13: Select “Federal Only” when asked if the income is taxable