Contractor Late Fees: What's Legal and How to Put It on Your Invoice

I used to think late fees were something only big companies charged. Then a client paid me 94 days late, and I realized I had been extending interest-free loans to people who were in no hurry to repay them. The next job's contract had a late-fee clause. That client has never paid late since. Funny how that works.

The one rule that matters: it must be agreed upfront

Can contractors legally charge interest or late fees on overdue invoices? Yes, in every state, as long as the late fee or interest rate is written into your contract or invoice terms and the client agreed to it before work started. That is the entire ballgame.

What you cannot do is add a late fee to an invoice after the fact just because payment is overdue. Trying to impose a charge retroactively, especially on an invoice already in dispute, is very hard to enforce. The fix is simple: add the clause to your contract or estimate template now, and it applies to every future job automatically.

What is a reasonable late fee?

Most contractors use one of two approaches:

Monthly interest: 1% to 1.5% per month on the unpaid balance. 1.5% monthly works out to 18% annually, which is the figure several state prompt-payment laws use for construction. This is the industry standard.
A flat fee: $25 to $50 per late invoice, better suited to small residential invoices where a percentage would be trivial.

On a $10,000 invoice paid 60 days late at 1.5% per month, the fee is $300. On a $1,000 invoice with a $35 flat fee, it is $35. Neither number is designed to make you rich. The fee exists to make paying late slightly more expensive than paying on time, and that nudge is worth more than the fee itself.

State limits you should know about

Late-fee rules vary by state, and you should check yours before making a rate official. A few examples of how different states handle it:

State	Rule of thumb
Georgia	Commercial accounts at least 30 days past due can be charged up to 1.5% per month
California	Contract debts without a stated rate default to 10% annually; agreed written rates are generally enforceable
Florida	Statutory rate (set quarterly, recently around 8%) applies when no contract rate is specified
Maryland (consumer contracts)	Caps consumer late fees and requires disclosure in at least 10-point bold type

This is a simplified snapshot, not legal advice. Rates and rules change, and commercial and consumer work are often treated differently. Check your state's usury limits, and if you do significant volume, have a local attorney review your standard terms once. It is a one-time cost that protects every invoice after it.

Exact wording to put on your invoice

Clarity beats legalese. Here is language that works:

Sample late-fee clause:

Payment is due within 15 days of the invoice date. Balances unpaid after the due date are subject to a late fee of 1.5% per month (18% per annum) until paid in full. A $35 fee applies to returned checks.

Put it in the terms section of every invoice and in your contract. When it appears on both, there is no argument about whether the client knew.

Government and commercial jobs work differently

On government and larger commercial projects, you often do not set the late fee at all. Federal, state, and municipal prompt-payment laws set specific interest rates that the paying party owes you if they are late. The federal Prompt Payment Act, for example, sets a rate that federal agencies owe contractors on late payments. If you are a general contractor managing subcontractors, learn both directions: what you can charge your clients, and what larger clients or agencies owe you when they pay late.

Several states also have construction trust-fund statutes that make it risky for a general contractor to delay paying subs after receiving payment from the owner, in some cases creating personal liability for the GC's officers. If you are a sub waiting on final payment, knowing whether your state has one of these is worth more than any late fee.

Do late fees actually make clients pay faster?

In my experience, yes, but not because anyone fears the fee. A $150 fee on a $10,000 invoice is not what moves the needle. What moves it is the signal: a contractor who prints late-fee terms is a contractor who tracks receivables, follows up, and will not let an invoice quietly age into oblivion. Clients prioritize the squeaky wheel, and printed terms make you squeaky before you ever have to say a word.

One more honest note: enforce your terms consistently or do not print them. A late fee you never collect trains clients to ignore everything else on your invoice too. When you do enforce one, do it calmly and in writing, with the math shown. "Per the terms on invoice 1042, a 1.5% late fee of $45 applies to the $3,000 balance, now 30 days past due." Professional, boring, effective.

This guide is general information, not legal advice. Late-fee and interest rules vary by state and between commercial and consumer work. Verify your rate against your state's current limits and consider having an attorney review your standard contract terms.

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Frequently asked questions

Can I charge a late fee if it was not in my original contract?

Generally no, not on an existing invoice. Add the clause to your contract or estimate template going forward, and it will apply to future jobs. Retroactive charges on invoices already in dispute are difficult to enforce.

What is a typical contractor late fee?

Most contractors charge 1% to 1.5% interest per month on the unpaid balance, or a flat $25 to $50 fee on smaller invoices. 1.5% monthly (18% annually) is the most common standard in construction.

Do I have to disclose the late fee a certain way?

It must be in your written terms before or at the time of billing, and some states have specific disclosure rules. Maryland, for example, requires consumer-contract late fees to appear in at least 10-point bold type. Check your state's requirements.

What if a government client pays late?

Federal and many state prompt-payment laws set the interest rate the agency owes you automatically. You generally do not set your own late fee on these jobs; the statute does it for you.