No you can't deduct all the interest that hasn't been deducted. If you had $100,000 in your IRA on December 31, and that balance included $5,000 of interest from US Government Obligations, then your distribution would include 5% US Government Interest. If your state allows for a deduction of the interest on the prorated portion of interest from US Government obligations, you would have to have been tracking the amount earned each year. Otherwise you would need to go back to your year-end statements to get the amounts.