Let's say an IO loan reverts to P&I (IO could not be extended for some reason.) I think I understand what happens when a 30-year SVR loan reverts after say 5 years: the repayment amount is recalculated based on the loan balance at the 5-year mark and a remaining loan term of 25 years. Standard repayment formula that gives a constant repayment amount (for a given interest rate) and will largely consist of interest at the start, and principal at the end. What about a LOC that is either partially or fully paid off and accruing less interest than when fully drawn? If the LOC limit is used for calculating the repayment amount, then it will be paid off much faster than 25 years. It seems the only logical way is to recalculate the repayment each month based on the current balance, and have the LOC limit reduced by the principal portion of that repayment?