Day 1 to Day 7: The gentle reminder window
The first follow-up should go out on the day the invoice is due — not as a threat, but as a friendly prompt. Most customers will pay within this window if reminded at all. The message should include the amount, a brief description of the work, and a one-click payment link. Tone: helpful, not urgent.
If there's no response by day 7, a second reminder is warranted. Same elements — amount, description, payment link — but with a slightly more specific call to action: 'Wanted to make sure this didn't get lost. Here's the link to settle your $1,200 balance from your Oct 15 service call.' Still friendly. No ultimatums.
Day 14 to Day 30: The voice call window
Invoices that haven't been paid by day 14 need a voice touchpoint. A human (or AI) voice communicates urgency in a way that text cannot. The call should be brief, professional, and focused on resolving the invoice — not cataloguing the customer's failure to pay on time.
'Hi, this is a call from ABC Plumbing regarding your October invoice. We'd love to get this sorted out. Your balance is $1,200 — you can pay online at the link I'll text you, or call us back at 555-1234.' That's the whole call. Under 30 seconds. Warm, not aggressive.
Day 30 to Day 60: The formal letter window
For invoices still unpaid at day 30, a formal written demand (email or mail) is appropriate. Tone shifts from friendly reminder to professional business communication. Include the invoice number, full amount, due date, and a clear deadline for payment (10-14 days from the letter date).
This is also when you should check whether there's a legitimate dispute. Sometimes invoices go unpaid because the customer is unhappy with the work or confused about what was charged. A direct conversation at this stage can often resolve the underlying issue faster than a collections escalation.
Day 60+: When to escalate
After 60 days of professional follow-up with no response or payment, you're likely dealing with either a genuine inability to pay or an intentional avoidance. At this point, options include: a payment plan offer (sometimes customers will pay over 3-4 installments what they won't pay in one), small claims court (effective for invoices under $10K), or a collection agency as a last resort.
Before going to collections, one final direct personal call from you (not an automated system) is often worth the effort. Sometimes the personal touch from the business owner cuts through in a way that automated systems don't. If that doesn't work, you've exhausted the professional options.