The client called. They cannot pay the full invoice this month. They are not refusing, they say, just short on cash. You can hang up and hope, or you can turn that phone call into a signed payment plan agreement that locks in the debt, sets a schedule, and gives you a paper trail if the second payment never comes.
When a Payment Plan Actually Makes Sense
A payment plan is the right move when the client acknowledges the debt but cannot pay in full right now. It is the wrong move when the client is disputing the work, ghosting, or stalling. Do not offer a plan to someone who has not even responded to your written demand letter. Offer it to someone who picked up the phone and asked for terms.
The other test: is the total recoverable in your state's small claims court? If yes, a signed plan that the client breaks gives you a near-automatic case for the full balance plus any accrued interest you wrote in.
What the Agreement Must Include
A payment plan agreement is a short contract. It does not need legal jargon, but it does need every one of these elements:
- Full legal name and address of both parties (yours and the client's)
- The original invoice number, date, and full balance owed
- The total amount being financed under the plan (including any late fees or interest)
- Payment amount, frequency (weekly, biweekly, monthly), and exact due dates
- Accepted payment methods and where to send payment
- A default clause: what happens if a payment is missed or late
- An acceleration clause: the full remaining balance becomes due immediately on default
- Signatures and dates from both parties
The acceleration clause is the most important line in the document. Without it, a missed payment only entitles you to that one missed amount. With it, one missed payment makes the entire remaining balance due, and you can sue for the full sum.
Setting a Schedule the Client Can Actually Hit
A schedule the client cannot meet is worse than no plan at all. Ask what they can pay each month, then push that number up by 10 to 20 percent. Keep the term under six months if you can. Long plans drift; short plans get paid.
Typical structures for a contractor invoice:
Typical payment plan structures for unpaid contractor invoices
Always require a down payment on signing. A plan with no money up front is a wish list. Twenty-five percent on signing is a reasonable ask, even on a hardship case.
Adding Late Fees and Interest
If your original contract included a late fee clause, that clause still applies and you can roll the accrued fees into the new balance. If it did not, you can still add a reasonable finance charge to the payment plan because the plan itself is a new agreement the client is signing. See the breakdown of typical rates in our guide on how to charge late fees.
Standard practice: 1 to 1.5 percent per month on the unpaid balance, or a flat $25 to $50 fee on any payment more than 5 days late. Check your state's usury cap before writing in anything above 18 percent annualized.
How to Deliver and Get It Signed
Send the agreement as a PDF by email the same day you spoke on the phone. Momentum matters. If you wait a week, the client's willingness to sign drops.
- Draft the document with the schedule you agreed to verbally
- Email it as a PDF with a short note: "Per our call, here's the plan in writing. Please sign and return by [date]."
- Use an e-signature tool (most have free tiers) so the client can sign on their phone
- Countersign and email the fully executed copy back within 24 hours
- File it with the original invoice and your contract
Do not start counting the first payment until you have the signed copy back. A verbal agreement to sign is not an agreement.
When They Miss a Payment
Send a reminder on day one past due. Reference the agreement by date and the specific payment that was missed. Give them five business days to cure before you invoke the acceleration clause. Most clients pay within that window because they know the alternative.
If the cure period passes, send a formal letter declaring the full balance due under the acceleration clause and giving a final 10 to 14 day deadline. From there, the path is the same as any unpaid invoice: a final demand letter, then small claims court. Our collections escalation timeline covers the next 60 days in detail.
Getting the Paperwork Right Without Guessing
A payment plan agreement is only as strong as the language inside it. A missing acceleration clause, a vague default definition, or no signature line for the client can turn a winning case into a long one. If the plan breaks down, the next document you send is a demand letter referencing the signed agreement and the missed payment. PaperHammer drafts that demand letter in three escalating versions, calibrated to your state's small claims limit, in about five minutes. You stay in control of the file, and the writing stops being the thing holding up payment.