Calculate Late Payment Interest and Fee Charges on Overdue Invoices — Free
Overdue invoices drain cash flow. Calculate statutory late payment interest and fixed recovery fees owed on overdue client balances.
The proof surface
Invoice generators create payment requests. This calculates interest accrued over days overdue plus statutory recovery fees for every unpaid invoice.
Why the flat version breaks
Forgiving late fees routinely
Failing to enforce contractual late fees encourages delayed payment habits.
Calculating monthly instead of daily
Statutory late interest accrues daily on overdue balances.
Ignoring statutory fee limits
Ensure statutory collection fees match local commercial law guidelines.
How to work the overdue penalty register
List each overdue invoice reference and total unpaid principal amount.
Record the number of calendar days past the agreed due date.
Enter the statutory or contractually agreed annual interest rate percentage.
See accrued interest and recovery fees per invoice and in total.
What the overdue penalty register replaces
| Question | Before | Visible working |
|---|---|---|
| Forgiving late fees routinely | Failing to enforce contractual late fees encourages delayed payment habits. | Specify days overdue |
| Calculating monthly instead of daily | Statutory late interest accrues daily on overdue balances. | Set interest rate percentage |
| Ignoring statutory fee limits | Ensure statutory collection fees match local commercial law guidelines. | Review penalty total |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Late payment interest arithmetic based on user inputs. Not legal or accounting advice; confirm contractual terms and commercial laws.
Data note: Everything runs in this browser tab on the overdue penalty register: your invoice reference | invoice amount | days overdue stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a bound register page
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the overdue penalty register reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The overdue penalty register reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the calculate late payment interest and fee charges on overdue invoices companionBoundary
Late payment interest arithmetic based on user inputs. Not legal or accounting advice; confirm contractual terms and commercial laws.
What this is built on
- Method: Enter the statutory or contractually agreed annual interest rate percentage.
- All sample records are invented examples. The app does not fetch measurements, policies, files or personal records.
- Google’s official pricing page, fetched 2026-09-28, lists free-tier access including AI Studio. Optional formatting only; limits and availability can change. Free-tier content may be used to improve products. Never paste private records there.
Before: Failing to enforce contractual late fees encourages delayed payment habits. After: the overdue penalty register shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this overdue penalty register, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.
Format my non-sensitive notes for a overdue penalty register. Return plain rows only: invoice reference | invoice amount | days overdue. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: invoice reference | invoice amount | days overdue. No AI response is executed as code.