On a macroeconomics level, however, it’s not so cut-and-dried, since it is unlikely in the extreme that all of the debt will have been converted to the new rate. It’s only the marginal debt that is paid at the high rate (the newest debt), but since we don’t know what the “very low interest rates” were, or how much debt was accrued under those rates or anything about the payment terms… @ragingloli‘s answer is the answer to the apparent homework question‽