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Overdue Interest & Delinquent Invoice Modeling

Free Invoice Late Fee Calculator

Calculate late fees and finance charges on delinquent invoices. Compare flat fees, monthly percentage interest (1.5%/month), and annual APR rates with customizable grace periods.

Invoice Late Fee Calculator

Flat, Percentage, Monthly & APR Overdue Interest
$
%/ mo

Late Fee Breakdown

45 Days Overdue
Original Invoice:$3,500.00
Days Delinquent:45 days
Fee Model:1.5% monthly recurring
Equivalent APR:18% APR
Calculated Late Fee:+$78.75
Updated Total Due

Original + Late Fee

$3,578.75

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Notice: Late-fee enforceability depends on written contract agreements and applicable statutory usury caps. This tool performs arithmetic only.

Monthly Recurring Interest

A common commercial benchmark is 1.0% to 1.5% per month (12% to 18% APR), prorated based on days past the scheduled due date, subject to local statutory limits.

Contract Agreement Best Practice

Late fee policies are typically established in writing beforehand within a signed contract or approved proposal rather than added after service delivery.

Grace Periods Build Goodwill

Offering a 5 to 7 day grace period prevents friction caused by bank ACH transfer lags, weekend delays, or AP accounting batch schedules.

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Frequently Asked Questions

Can I charge a late fee on an overdue invoice?

In standard commercial practice, late payment fees or interest should be agreed upon in writing (such as a signed client contract, master services agreement, or approved estimate) prior to delivering work. Applicable statutory laws and regulations also cap maximum allowable interest rates depending on jurisdiction and customer type.

What is the standard commercial late fee rate?

A commonly used benchmark in commercial B2B invoicing is 1.0% to 1.5% per month (equivalent to 12% to 18% annual APR) on outstanding overdue balances, often applied after a grace period of 5 to 10 days. Some businesses use flat administrative fees (e.g. $25–$50) for smaller balances, subject to local regulatory caps.

Should late fees be listed as a separate invoice or updated total?

Best practice is to issue an updated statement or revised invoice showing the original principal balance, the itemized late fee calculation with days delinquent, and the revised total balance due, accompanied by a polite reminder letter.

Does Invoza give legal advice on collections?

No. This calculator performs arithmetic and financial interest modeling only. Statutory limits, usury ceilings, and contract enforceability vary significantly by state and country. Consult qualified legal counsel for dispute resolution.