Do you only issue invoices on a particular day of the month?

Even if so, say you produce and send invoices on the 5th, or the last, day of every month for the month before, with 45 day terms you're going to have overlapping data from January and February into March.

I'm going to assume that the invoice data on the left is a summary from somewhere else, where individual invoices with individual dates exist and are summed or pivoted into what you have there.

If you invoice all month long, different invoices from March with a 45-day cycle could become past due in both April and May. So how do you decide how much money to allot to April and how much to May? The 30- and 60-day ones, again presuming all invoices have the same date for the month, are fairly straightforward, but the 45-day cycle won't really work in this style unless you had specific date information.

Best bet, to me, would be to apply the terms to each individual invoice in a spreadsheet which includes the date of the invoice, then for Client B, an invoice sent on 2/6/23 would become past due on the 46th day, or 3/24/23. Then on any given day you could filter for which invoices, and sum up to accounts, were past due.