An unpaid invoice rarely gets resolved by waiting, and almost never by a single angry email. What works is a calm escalation ladder: each step raises the pressure slightly, gives the client a clean way to pay, and creates a paper trail in case you need the later steps. Climb it one rung at a time.
Step 1: the reminder sequence
Before anything else, make sure the client has actually been reminded — in writing, more than once, with the invoice attached each time. A due-date nudge, a note at one week overdue, another at two weeks, and a final notice around 30 days. Use the copy-paste emails in late payment reminder templates. A surprising share of "clients who won't pay" turn out to be invoices stuck with the wrong person or in an approvals queue; the reminder sequence flushes those out cheaply.
Step 2: pick up the phone
Email is easy to ignore; a phone call isn't. Call the person who hired you (not accounts payable) and keep it collaborative: "Invoice 187 is a month overdue and my emails aren't getting traction — what's going on on your end, and how do we get it sorted this week?" Take notes during the call, then send a same-day email summarizing what was agreed ("As discussed, you'll process payment by Friday the 12th"). That email converts a verbal promise into a written one.
Step 3: offer a payment plan
If the honest answer is "we can't pay right now," a payment plan beats a standoff. Partial money now is worth more than a full amount you may never see. Keep it tight: 2–4 installments, first one immediately, in writing, with the condition that any new work waits until the plan completes. Invoice each installment separately so every payment has its own document and due date.
Example: first installment of a 3-part payment plan
The line item references the original overdue invoice and states the full plan, so the paper trail stays clear.
Step 4: stop work and withhold deliverables
If you're still doing work for this client, pause it — politely, in writing: "I've paused work on the site until the outstanding balance is cleared; happy to resume the day it's paid." If final files, source code, or a launch are still in your hands, they stay in your hands until payment. This is your strongest practical leverage, which is exactly why final payment should always come before final delivery — a habit worth adopting from the deposit stage onward (see how to ask for a deposit upfront).
Step 5: the demand letter
A demand letter is a formal written notice that states the amount owed, references the invoice and prior reminders by date, sets a specific deadline (commonly 7–14 days), and says what happens next — typically that you'll pursue the debt through the courts or a collections agency. Send it in a way you can prove was delivered. A letter on a lawyer's letterhead costs relatively little and often produces payment by itself, because it signals you're genuinely prepared to escalate.
Step 6: small claims, collections, or writing it off
If the deadline passes, you generally have three options, and the right one depends on the amount and your jurisdiction:
- Small claims court — designed for individuals without lawyers; suited to modest amounts. Your invoice, contract, and reminder trail are your evidence.
- A collections agency — they take a significant cut (often a third or more), but require no time from you.
- Writing it off — for small amounts, the rational choice is sometimes to stop spending hours chasing hundreds. Ask your accountant how to record it.
Procedures, limits, and rules differ by location, so check how small claims works where you are before filing.
How to stop this happening again
Every non-payment story has the same prevention list: take a deposit, invoice promptly with clear terms and a stated late fee (wording here), run reminders on a fixed schedule, and stop work early rather than late. Clean, professional invoices are the foundation of that paper trail — InvoiceKo creates them free in your browser, with no signup and no watermark, including the notes and terms fields where your payment terms and late-fee clause live.