Payment terms are the difference between an invoice that gets paid and one that gets processed whenever somebody gets round to it. They cost nothing to set and almost nobody sets them deliberately.

"30 days" is not one thing

Thirty days from what? From the invoice date, from the end of the month in which the invoice fell, from delivery, from the customer's approval of the work?

Those are wildly different in practice. "30 days from invoice" on the 2nd of the month means payment early the following month. "30 days from month end" on the same invoice means payment two months later. Large customers routinely operate the second and describe it as the first.

Write which one you mean. If a customer's own terms differ from yours, that is a negotiation to have before the work, not a discovery to make after it.

The terms worth having

  • When payment is due, stated unambiguously.
  • What triggers the invoice — completion, delivery, a milestone, a date.
  • A deposit, where the work involves cost to you before payment.
  • What happens when payment is late. Interest, suspension of work, or both. Stating it is what makes it available to you later.
  • Who to invoice, and how. The name, the email, and whether a purchase order number is required. Ask before you start.

Shorter is usually available

Thirty days is a convention, not a law. Plenty of small businesses work on fourteen days, on payment before delivery, or on deposit plus balance — and customers accept it because it was stated at the outset as the way you work.

The terms you get are largely the terms you ask for. Businesses that quietly default to 30 days because it seems standard are financing their customers for a month at their own cost.

Interest on late payment

You can charge it where it has been agreed, which means it needs to be in the terms the customer accepted before the work — not added to an overdue invoice afterwards.

In practice most small businesses never actually charge it. Having it there still helps: it makes the lateness a defined breach rather than an inconvenience, and it gives you something to waive as a gesture when you agree a payment plan.

Say it once, clearly, at the start

The terms belong on the quote, on the order confirmation, and on the invoice. Three places, the same words. That is not repetition for its own sake — the person who accepted the quote is often not the person who processes the invoice, and each needs to see it.

Then apply them consistently. Terms that are enforced for some customers and not others stop functioning as terms and become a matter of who asks.

General guidance on commercial practice, not legal advice. Rules on interest and on business terms change; take advice where a contract is substantial.