An overdue invoice and a client who genuinely won't pay are different problems, and treating the first like the second — escalating too fast, too aggressively — can damage a relationship that would have resolved itself with one more email. Here's a staged approach that matches your response to what's actually happening.
Stage 1 (Day 1–10): Assume it's an oversight
Most late payment is forgetting, not refusing. A gentle reminder at day+1, a follow-up at day+5, and a firmer note at day+10 resolves the large majority of overdue invoices without anything more serious being needed. See reminder templates for each of these stages.
Stage 2 (Day 10–20): Get a direct answer
If reminders go unanswered past 10 days, stop sending variations of the same email and ask a direct question instead: "Can you confirm you've received this and let me know when I can expect payment?" A client who intends to pay will usually respond to a direct question even if they've been ignoring generic reminders. Silence at this stage is itself useful information.
Stage 3 (Day 20–30): Escalate the tone, not the threats
If there's still no response, a firmer, more formal email is appropriate — referencing the original agreement, restating the amount owed, and giving a specific date by which you need payment or a response. If your contract includes a late fee clause, this is the point to apply it. Avoid vague threats ("or else") without a concrete next step behind them — they weaken your position if you don't follow through.
Stage 4 (30+ days): Decide whether this is worth pursuing formally
For UK-based work, a formal Late Payment of Commercial Debts letter before action, small claims court (for amounts under £10,000), or a debt collection agency are the realistic next steps. Weigh the invoice amount against the time and cost of pursuing it — for small amounts, this is often where you decide whether to formally pursue or write it off, which is a legitimate business decision, not a failure.
How to avoid reaching Stage 4 in the first place
Almost every case that reaches formal recovery started as an ordinary overdue invoice that never got a consistent follow-up. Missed or forgotten reminders, not deliberate refusal, are the largest single cause of late payment — which is exactly the gap AutoChase's auto-chase sequence closes: a fixed gentle → follow-up → final schedule that runs whether or not you remember to send it yourself.