Late Fee on a $1,000 Invoice, 30 Days Overdue
Interest at 1.5% a month
$15.00
1.5% a month, simple interest charged pro rata by day, with no flat fee added.
How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Unpaid invoice amount1000 $
- Late fee rate you wrote in the contract1.5 % per month
- Days past due30
- Flat fee, if your contract has one0 $
Now owed$1,015.00
| Original invoice | $1,000.00 |
|---|---|
| Days late | 30 (1 months) |
| Interest at 1.5% a month | $15.00 |
| Flat fee | $0.00 |
| Total now due | $1,015.00 |
| Annual rate this equals | 18% |
| Per day from here | $0.50 |
Days past due compared
Interest is simple and pro rata by day, so it climbs in a straight line rather than accelerating.
| Days past due | Now owed | Total now due |
|---|---|---|
| 30 days | $1,015.00 | $1,015.00 |
| 60 days | $1,030.00 | $1,030.00 |
| 90 days | $1,045.00 | $1,045.00 |
| 120 days | $1,060.00 | $1,060.00 |
What else matters here
A thousand dollar invoice at 1.5 percent a month earns $15 of interest in 30 days. The total due becomes $1,015 and it climbs 50 cents a day after that.
Fifteen dollars is not the point on an invoice this size. The point is the clause. A customer who sees a late fee line on the second invoice learns that your terms are real, and that lesson is worth far more than the interest ever will be on small tickets.
If small invoices go late often, a flat administrative fee is usually a better deterrent than a percentage. Put it in the flat fee field and it is added on top, but only if your contract already says so.
What this calculator assumes
- A late fee is only collectable if it was in the contract or on the invoice before the invoice went late. A fee that first appears in a reminder email is not enforceable anywhere.
- 1.5 percent a month is 18 percent a year and is the common trade figure, but states cap this. Several cap it below 18 for consumer work, and a rate over the cap can void the whole fee clause, not just the excess.
- Interest here is simple, charged pro rata by day. Compounding monthly is legal in some states and not others, so the simple figure is the safe one to put on paper.
Questions people ask
What is the late fee on a $1,000 invoice at 30 days?
$15 at 1.5 percent a month, making $1,015 due in total.
Can I charge a late fee if it was not in the contract?
No. A late fee is only collectable if it was in the contract or printed on the invoice before that invoice went late. A fee that first appears in a reminder email is not enforceable anywhere, however overdue the money is.
Is 1.5 percent a month legal everywhere?
Not everywhere. One and a half percent a month is 18 percent a year and it is the common trade figure, but states cap this and several cap it below 18 for consumer work. A rate over the cap can void the entire fee clause rather than just the excess, so check your own state before printing it.
The late fee calculator takes any dimensions you like and hands back the same list.