Invoice due date calculator

Three term engines sit behind the presets: plain net days, the end of the invoice month plus an offset, and prox terms where a delivery after the cut-off pushes the cycle to the next month. Both the contractual date (what the terms say before rolling) and the rolled due date stay on screen, because invoice disputes often turn on which of the two applies. The annualized discount cost uses the standard trade-credit rate, d/(1-d) times 365 over the days between the discount deadline and the due date, so you can compare it with your own borrowing cost. Everything runs in this tab; nothing is uploaded.