By the time an invoice is 30 days past due, another polite nudge isn't the right move. A friendly follow-up cadence works for the first couple of weeks, when the most likely explanation is a slow AP process. Past that point, treating a genuinely stalled payment like a normal follow-up is the mistake — it needs to be handled as a recovery problem, not a reminder problem.
Move off email once the follow-up cadence has run out
If you've already sent the friendly nudge and the direct follow-up and gotten silence, a third email rarely produces a different result — it just gets filed next to the other two. A phone call forces a real-time answer in a way an email can't: either your contact picks up and tells you what's actually holding it up, or they don't pick up at all, which is information too. Keep the call short and specific — you're not asking permission to be paid, you're asking for a payment date.
"Hi Sam — following up by phone since the last couple of emails haven't gotten a response. Invoice 041 for $4,200 is now 32 days past due. Is there something on your end holding it up, or can you give me a specific date I can expect payment by?"
If your contact has gone quiet, find someone else in the building
Sometimes the person you've been emailing genuinely doesn't control payment — they're not stonewalling you, they just have no leverage over accounts payable and are avoiding an uncomfortable status update. Once a week of silence follows a missed promised date, it's reasonable to go around them. Look for a finance or operations contact on the company site, check LinkedIn for someone with "accounts payable" or "finance" in their title, or ask your original contact directly for who handles vendor payments. A short, factual email works better than an apologetic one here — you're not interrupting, you're routing a legitimate request to the right desk.
Apply a late fee only if the contract says you can
A late fee only has teeth if it was agreed to in writing before the work started. If your retainer agreement or proposal states a late payment percentage, this is the point to invoke it — reissue the invoice with the fee added as its own line item and reference the specific clause. If your agreement is silent on late fees, don't invent one now; adding a penalty the client never agreed to gives them a legitimate reason to dispute the whole invoice instead of just paying it. That gap is worth fixing for every future engagement, just not this one.
Know when to bring in outside help
Collections agencies and small-claims court are last resorts, not second steps — both cost time, and a collections agency typically keeps 20-50% of whatever it recovers. They start to make sense once a specific, promised payment date has already been missed and the client has stopped responding to calls and emails altogether. Small claims is usually the better option for amounts under your state's limit (commonly $5,000-$10,000): it's cheaper than a collections cut and doesn't require a lawyer, but it does mean the client relationship is effectively over either way. Before filing, send one final written demand by email referencing the invoice number, amount, and due date — courts generally expect to see that you attempted resolution first.
None of this replaces a clean, well-worded invoice with a real follow-up cadence in the weeks before it's overdue — that ground is covered in how to get consulting invoices paid faster. This is what to do once that cadence has already run its course and the invoice is genuinely stuck. The free Consulting Invoice Generator makes it easy to reissue an overdue invoice with a stated late fee and a clean paper trail attached to it.