Can I Change a Customer's Payment Terms?

Why you cannot just switch

If you have agreed terms with a customer, those terms form part of your contract with them. Moving someone from net 30 to net 14 is a variation to that contract, and a variation normally needs the other side's agreement to be binding. You cannot simply print new, tighter terms on the next invoice and treat them as though the customer had signed up to them.

Imposing tighter terms unilaterally is also a fast way to start a dispute you did not need. If the customer never agreed to the change, they have a ready-made reason to ignore it — and a convenient excuse to query the invoice when you chase it. The better path is to treat a change of terms as exactly what it is: a fresh agreement that the customer needs to accept, ideally in writing, before it takes effect.

Give reasonable notice

The safe approach is to notify the customer in writing and apply the new terms only from a specified future date, never retrospectively. For example: "From 1 August 2026, our standard terms move to net 14. Invoices issued before that date remain on your current terms." That gives a clean cut-over and avoids any argument about which invoices the change covers.

Reasonable notice also gives the customer time to adjust their own cash flow and accounts-payable schedule, and it signals that you are acting fairly rather than springing a surprise on them. Email is perfectly adequate for this — there is no need for anything formal — but what matters is that you keep a clear written record of exactly what changed and when, so the new terms are easy to evidence later if the customer disputes them.

If the customer pushes back

A customer is entitled to decline a variation, and some will. If they do, you still have several options: keep their existing terms for the time being, tie the change to the next order or a contract renewal, or require a deposit on future work instead of shortening the headline term. For a genuinely risky payer, you can also move them toward shorter terms or stop credit as their behaviour justifies it.

Tying tighter terms to a fresh agreement — a renewed contract, a new purchase order, or an updated credit application — is often the cleanest path of all. It sidesteps the variation problem entirely, because the new terms apply to a new arrangement that the customer has actively signed up to, rather than being imposed on an existing one they never agreed to change.

Make the change stick

Once the customer accepts, update your terms of trade and your invoicing system so the new term applies automatically going forward — you do not want to be remembering to change it by hand on each invoice. Confirm the change back to the customer in writing, keep that confirmation on file, and repeat the new term on every invoice from the effective date so there is a consistent paper trail.

Consistency is what makes the change hold: if some invoices still show the old term after the cut-over, you hand the customer an argument about which one really applies and weaken your position. One clear effective date, applied the same way everywhere, keeps the change clean, easy to evidence, and enforceable if you ever have to rely on it.