How to Chase an Unpaid Invoice (Without Losing the Client)
The work is done, the invoice is sent, and the due date has quietly come and gone. Chasing an invoice isn't a confrontation — it's a process. This is the full playbook: why clients pay late, a day-by-day escalation timeline, and what to do at 30, 60, and 90 days.
By KSP Labs, Software Studio behind Billify · Updated August 2026
Chasing several invoices? Open the free editor (no signup) — exact due dates, payment terms, and a sent/paid/overdue history that tells you who needs chasing today.
Open the free invoice editorNot legal advice. Late-fee rules, statutory interest, and small-claims procedures vary by country and change over time — confirm with a qualified accountant or lawyer before relying on any of it.
Why clients pay late (and why it's rarely personal)
Before you fire off an annoyed email, understand the actual causes. Most late payments are disorganization, not malice — and the cause determines the fix.
1. The invoice never reached accounts payable
Your contact loved the work — but the invoice sat unread in their inbox, or got forwarded to an AP address that filtered it out.
2. The client pays on a payment run
Many companies batch payments once or twice a month. Miss the cutoff by a day and you wait for the next cycle — regardless of your due date.
3. Missing or incorrect details
No PO number, wrong billing entity, no tax ID, unclear payment method — AP departments routinely reject invoices for these and may not tell you.
4. Cash-flow problems
The client is choosing who gets paid first. Vendors who chase politely and consistently get moved up the queue; silent vendors get deprioritized.
5. Strategic lateness or bad faith
Some large companies deliberately pay at 60–90 days because vendors tolerate it; a few clients never intended to pay. Consistent pressure handles the first — the escalation ladder handles the second.
The escalation timeline: what to do, and when
Treat follow-up as a calendar, not a mood. Each step is short, dated, and slightly firmer — and every message becomes evidence if you ever need to escalate for real.
Day −3 (before the due date) — Friendly heads-up
A short note before the due date catches the "invoice never reached AP" problem early and respects payment-run cutoffs: "Invoice #2041 for €2,400 is due Friday — is there anything you need from me to get it processed?"
Day +1 (overdue) — Short, factual nudge
One short paragraph: invoice number, amount, due date, and a request for a payment date — not "please look into it." Attach the invoice again; never make them search for it.
Day +7 — Firm but polite follow-up
Reference your previous emails, restate the amount and days overdue, and ask whether something is blocking payment — a missing PO number, tax ID, or a payment-run you both missed. Offer to fix it today.
Day +14 — Switch channels: phone, then recap
Calls are harder to ignore than email. After the call, send a written recap: "As discussed, you confirmed payment will be sent on the 15th." A dated written confirmation is evidence; a phone call is not.
Day +30 — Final demand letter
Formal, factual, unemotional: exact amount, deadline (typically 10 business days), accrued late fees if disclosed in advance, and the specific next step — collections or small claims. Many invoices are paid within 48 hours of this letter.
Day +45 and beyond — Escalate
File in small claims court (usually worth it between ~$500 and your local limit), hand off to a collections agency, or have a lawyer send a demand letter above that. The paper trail you built — contract, invoice, follow-ups, final demand — wins most straightforward cases.
Setting better terms up front means the next chase starts three weeks later than this one did — the full framework is in the invoice payment terms guide.
Make the next invoice un-chaseable
- Invoice the day you deliver. The work is freshest, the goodwill highest, and your cash-flow clock starts weeks earlier.
- Take a deposit (30–50%) on anything over a couple of weeks' effort. A client who won't pay a deposit is telling you something.
- State an exact due date and a named payment method on every invoice — see the payment terms guide.
- Give AP zero reasons to reject: PO numbers, correct legal entities, tax IDs. The invoice field checklist is literally this list.
- Track status, not memory. A sent/paid/ overdue view of every outstanding invoice — which is what Billify's invoice history gives you, free and without an account — turns chasing from dread into a Tuesday routine.
- Fire the pattern, not the incident. One late payment is life; a second is information; a third is a decision.
Frequently asked questions
How do you politely ask for payment?
Be brief, specific, and assume good faith: reference the invoice number and amount, state how overdue it is, ask for a payment date (not just "please look into it"), and offer to fix any blockers ("if you need a PO number or different billing details, tell me today"). Politeness comes from tone, not from vagueness.
What do you say when a client ignores your invoice emails?
After two ignored emails, switch channels: call them, then send a written recap of the call ("as discussed, you confirmed payment on [date]"). If both stall, send the formal final-demand letter at day 30 — specific amount, deadline, and next step. Silence in response tells you it's a can't-pay or won't-pay problem, not a forgot-to-pay problem.
Can I charge interest or a late fee on an overdue invoice?
Only fees you disclosed in advance — on the invoice or in a signed contract — are safely enforceable. 1–1.5% per month or a small flat fee is the common commercial range. In EU and UK business-to-business transactions, statute implies interest and fixed compensation even without written terms (EU: reference rate + 8pp and €40 minimum; UK: base rate + 8% and £40–£100). Check your jurisdiction's current rules before enforcing.
Is it worth taking an unpaid invoice to small claims court?
Usually yes for amounts between roughly $500 and your local small-claims limit: filing fees are small, lawyers aren't required in most jurisdictions, and a complete paper trail (contract + invoice + follow-ups + final demand) wins most straightforward cases. Below ~$300, the time cost typically exceeds the debt; above the limit, weigh a lawyer's demand letter or collections instead.
Should I keep working for a client who pays late?
Use the pattern rule: one late payment, chase and move on; a pattern of lateness, require deposits and shorter terms or pause new work until the balance clears (say so in writing — it's your strongest lever); chronic severe lateness, replace the client.
What is a final demand letter for an unpaid invoice?
A formal, factual notice that payment is due within a set number of days (typically 10 business days) or you will escalate to collections or court. It states the invoice number, amount, dates, accrued late fees, the exact deadline, and the specific escalation step, with all invoices and correspondence attached. It's both your strongest pre-legal leverage and the evidence a court or agency will want to see.
Chase like a professional, get paid like one
Late payments are a process problem, not a personality conflict. Put terms, due dates, and payment methods on every invoice — and track status — so the next chase starts three weeks later than this one did.