Skip to content
CalcWolf Business Invoice Late Fee Calculator
Business

Calculate Late Payment Fees

Calculate late fees on overdue invoices. Daily, monthly, and total penalties by amount and terms.

📅 Updated April 2026 Formula verified 📖 4 min read 🆓 Free · No sign-up

Standard Late Payment Terms

The most common late fee structure: 1.5% per month (18% APR) on outstanding balances, applied after a 30-day grace period. Some businesses charge a flat fee ($25-50 per late payment) instead of percentage. Your invoice must clearly state the late fee terms to be enforceable. Most states cap late fees at 1.5-2% per month (18-24% APR).

Enforcing Late Fees

Three keys to collecting late fees: 1) Include clear terms on every invoice ("1.5% monthly late fee on balances over 30 days"). 2) Send payment reminders at 7, 14, and 30 days past due. 3) Follow through consistently — waiving fees trains clients to pay late. Accounts receivable automation tools (QuickBooks, FreshBooks) send reminders and calculate fees automatically.

⚡ CalcWolf Insight

The average small business has $84,000 in unpaid invoices at any given time. Offering a 2% discount for payment within 10 days (common terms: "2/10 Net 30") costs you 2% but eliminates 30-60 days of cash flow delay. For businesses with tight cash flow, the discount pays for itself through reduced borrowing costs.

Frequently asked questions
What is a reasonable late fee to charge?
1-1.5% per month is standard and legally acceptable in most states. 2% per month (24% APR) is the maximum in many jurisdictions. Flat fees of $25-50 per late payment are common for smaller invoices. Check your state laws — some states cap late fees or require specific disclosure language.
Can I charge interest on unpaid invoices?
Yes, if your invoice terms specify it. Include a clause like: "A late fee of 1.5% per month will be applied to invoices unpaid after 30 days." This becomes part of the contract when the client agrees to your terms. Without stated terms, you may not be able to legally collect late fees.
✓ Math logic verified against primary sources → See our verification process
Kevin Glover
Founder, CalcWolf · GLVTS · Blickr
All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →
🐛 Report a Calculator Error
Found a bug or outdated data? Reports go directly to Kevin and are reviewed personally.