You delivered the work. The invoice is weeks overdue. And somewhere in your contract there's a line about a "late fee" you've never actually charged, because you're not sure you're allowed to, or how much, or how to bring it up without torching the relationship.
Let's fix that. Here's the practical version for freelancers.
Can you even charge a late fee?
Generally, yes, if it's in your contract or on the invoice before the work starts. A late fee you invent after an invoice goes unpaid is much harder to enforce. So the real move is to put it in writing up front, where it quietly does its job: clients pay on-time invoices faster when they know there's a clock.
(Exact rules vary by country and sometimes by state/region, check your local statutory limits. This is a practical guide, not legal advice.)
How much is normal?
Two common structures freelancers use:
- Percentage per month, e.g. 1.5% per month on the overdue balance (works out to ~18%/year). This is the most common and scales with how late they are.
- Flat fee, e.g. $25, $50 per overdue invoice. Simple, predictable, good for smaller invoices.
A reasonable, defensible default is 1.5% per month after a short grace period. High enough to matter, low enough to look professional rather than punitive.
Put it in your contract (steal this line)
"Invoices are due within [15] days. Balances unpaid after the due date accrue a late fee of 1.5% per month (or the maximum permitted by law), calculated from the due date."
That single sentence does more for your cash flow than any chase email.
How to actually bring it up
When an invoice crosses into "seriously late," a vague threat ("there may be fees") gets ignored. A specific number doesn't. Compare:
- ❌ "Please note late fees may apply."
- ✅ "As per our agreed terms, the invoice is now 21 days overdue, so a 1.5%/month late fee of $15 applies, total now due $1,215. Please confirm when I can expect payment."
The second one is calm, factual, and impossible to misread.
Don't do the math by hand
Working out the fee for each late client is exactly the kind of friction that makes you skip it. I built a free late fee calculator, enter the invoice and due date, and it gives you the fee, the new total, and the ready-to-send line above. No sign-up.
And if tracking which invoices are late (and what each one now owes) is the real headache, that's the whole point of Get Paid OS: it counts the days overdue automatically and hands you the email, fee included, as the Follow-Up Playbook, or the full app.
The takeaway
A late fee isn't about squeezing clients. It's a polite, pre-agreed incentive to pay on time, and most of the value comes before you ever charge it, just from clients knowing it exists. Put the line in your contract today. Future-you, chasing a 30-day-late invoice, will be grateful.
Do you charge late fees? What structure works for you, flat or percentage? Curious what other freelancers actually do.
