How to track who has paid, and who is behind

Start from the member list, not the payments

A list built from who has paid always looks complete, because the people who have not paid are simply absent from it. Build the list from every member instead, and mark each as paid or not. The gaps are the point.

This is why a grid works: every member has a row whether or not they have contributed, so an empty cell is visible rather than invisible.

Record the expected amount, so 'behind' means something

'Behind' only has a meaning if there is a figure to be behind against. Write down what each member is expected to give per month — the same for everyone, or different where the group has agreed it — and the shortfall calculates itself.

Someone who pays in two instalments is not two separate entries to reconcile. Both land in the same month and add up; what matters is whether the total reached the expected amount.

Handle prepayments without losing track

A member who pays three months up front should read as up to date for three months, not as having overpaid once and then fallen behind twice. Carry the surplus forward against the months it covers.

The same applies in reverse: a shortfall does not carry backward. If March was short, March stays short even after April is paid in full.

Keep the chase list separate from the record

The month-by-month record is for everyone. The list of who to remind this week is for the treasurer. Being able to switch to 'show only those who still owe', with the amount beside each name, turns a review meeting into a two-minute task.