How to write a simple payment agreement?

To write a simple payment agreement, put six things on one page: both parties' names, the total amount owed and what it is for, the payment schedule with exact dates and amounts, the payment method, what happens on a missed payment, and dated signatures.

Between two parties, the schedule is the part to make painfully specific. $500 on the first of each month from August through December beats monthly installments. Add a late fee and a grace period so a missed date has a defined consequence instead of an argument.

Writing up a payment plan this way takes fifteen minutes and turns a loose promise into an enforceable document. Keep a signed copy each, and record every payment against it as it lands.

This payment plan contract template asks for each of those six items as a field.