Late fee calculator for overdue invoices
A 1.5% monthly late fee is ~18% a year. See what slow payment really costs.
A late fee is the interest you charge a client for the loan they take out when they pay you late. Enter the invoice, how overdue it is, and your policy, and this calculator shows the fee — and what it looks like as an annualized rate.
Why a late fee is a pricing tool, not a punishment
Most freelancers add a late fee because a client stiffed them once. The better reason is that slow payment is expensive for you: the money sitting in someone else’s accounts payable is cash you cannot use to pay your own bills, and chasing it costs you hours. A late fee does two jobs at once — it recovers a little of that cost, and it makes paying you on time the path of least resistance for the client.
This calculator shows what a given late-fee policy actually costs the client, expressed both as a dollar figure now and as an annualized rate. That second number is the eye-opener: a modest-sounding 1.5% per month is about 18% a year, steeper than a typical business credit card. Put that in your contract and clients suddenly find your invoice in the "pay this week" pile.
The three ways to charge
Monthly percentage. The most common and usually the fairest: a percentage of the unpaid invoice for every 30 days it is late (1%–2% is typical). It scales with the invoice, so a big late bill costs the client more — which is exactly the incentive you want.
Daily fee. A flat dollar amount per day overdue (often $25–$50). Simple to understand but brutal in the annualized math, and some states cap or disallow per-day charges on certain contracts. Use it where it is legal and where you really want to signal zero tolerance.
Flat fee. A one-time charge the first time an invoice goes overdue. Gentle and easy to accept, but weak as a behaviour changer because it does not grow the longer they wait.
What the annualized rate really means
The "annualized equivalent" line converts the late fee into the language of interest rates so you can compare it to other forms of credit. A monthly fee compounds in effect because each month the balance (invoice plus accrued fee) is what the next month’s percentage applies to — but for a short overdue period the simple annualization the calculator shows is close enough to make the point. The point is not the exact APR; it is that a late fee is a loan you are making to the client at a high rate, and you should be paid for it.
Making it enforceable
A late fee you never put in writing is a wish, not a term. The clause belongs in your contract and on the invoice itself ("Late after 30 days; 1.5% per month thereafter"). Some states require the fee to be a reasonable estimate of your actual collection cost, and a few limit how high it can go or ban per-day charges — so check your state’s rules for the kind of work you do. Even where the law is loose, an unreasonable fee is harder to collect and easier for a client to dispute, so keep it in a defensible range.
The fee also has tax treatment worth knowing: late fees you charge are ordinary business income to you, and a late fee a client charges you is a deductible business expense. Neither side gets a free pass.
Using it without poisoning the relationship
Charge the fee, but charge it politely. Many freelancers waive the first one as a goodwill gesture and only enforce it on the second late payment — the policy exists to change behaviour, not to nickel-and-dime good clients through a rough month. The calculator lets you show a client, if they ever push back, exactly what their slow payment is costing in annualized terms; most people pay up once they see the number.
An estimate for planning, not legal advice. Late-fee enforceability and caps vary by state and contract type; the calculator shows the arithmetic, not whether a given fee is legal where you work. See the disclaimer and confirm against your state’s rules before relying on a clause.
Frequently asked questions
What late fee should I put in my contract?
A monthly percentage of 1% to 2% of the unpaid invoice is the most common and usually the most defensible. It scales with the bill, so larger late payments cost the client more, which is the incentive you want. A flat per-day fee is harsher and is restricted or banned in some states, so check local rules before using one.
Is a 1.5% monthly late fee really that expensive?
Yes — about 18% annualized, which is higher than most business credit cards. That is intentional: the steep effective rate is what pushes your invoice to the top of the client’s payment queue. The calculator shows the annualized equivalent for whatever policy you enter.
Are late fees taxable?
For you, late fees you charge a client are ordinary business income and are taxable. If a client charges you a late fee, it is a normal business expense you can deduct. Neither side treats it as anything special for tax purposes.
Can a client refuse to pay the late fee?
They can dispute it, which is why the fee must be in your signed contract and ideally noted on the invoice. An unreasonable fee is harder to collect and easier to challenge, so keep it in a defensible range. Some states also limit how high a late fee can be or require it to reflect your actual collection cost.
Should I actually enforce the late fee every time?
Many freelancers waive the first late fee as a goodwill gesture and only enforce it on repeat offenders. The policy exists to change payment behaviour, not to nickel-and-dime a good client through one rough month. Enforce it consistently from the second occurrence so clients learn it is real.
Does the annualized rate compound like interest?
In practice a monthly percentage applies to the growing balance, so it compounds — but for the short periods an invoice is typically overdue, the simple annualization the calculator shows is close enough to make the point. The exact figure matters less than seeing that a "small" monthly fee is a high-rate loan you are extending to the client.