【How-to】How much interest does the irs pay on late refunds

Calculate the interest you will pay over the life of the loan using the formula I = R x T, where I = interest, R = rate and T = time. If you borrowed $10,000 at 4 percent interest for one year, replace the letters in the formula with the numbers from your loan. For example, 0.04 x 1 x $10,000 = $400.