Calculator Form
Use advanced payment rules, grace periods, holidays, discounts, and aging controls.
Example data table
These sample rows show how different terms, adjustments, and discount windows affect the final payment date.
| Invoice | Invoice Date | Terms | Grace Days | Adjustment Rule | Discount Window | Final Due Date |
|---|---|---|---|---|---|---|
| INV-1001 | 2026-03-12 | Net 30 | 0 | Following | 2% in 10 days | 2026-04-13 |
| INV-1002 | 2026-03-18 | EOM + 15 | 2 | Modified following | 1.5% in 7 days | 2026-04-17 |
| INV-1003 | 2026-03-27 | End of month | 0 | Preceding | None | 2026-03-31 |
| INV-1004 | 2026-03-29 | 15th next month | 3 | Following | 3% in 5 days | 2026-04-20 |
Formula used
Base due date depends on the selected term structure:
Net terms: Due seed = Base date + Term days
EOM plus days: Due seed = Month-end(Base date) + Term days
End current month: Due seed = Month-end(Base date)
Fixed day next month: Due seed = Selected day in next month
Grace adjustment
Due with grace = Due seed + Grace days
Business-day adjustment
Final due date = Adjust(Due with grace, rule, weekends, holidays)
Discount deadline
Discount deadline = Base date + Discount days
Overdue and aging
Days overdue = max(Reference date - Final due date, 0)
Days remaining = max(Final due date - Reference date, 0)
Payment value
Potential discount = Invoice amount × Discount rate
Estimated late fee = Invoice amount × Monthly late fee rate × (Days overdue / 30)
Amount due now = Invoice amount + Estimated late fee - Applied discount
How to use this calculator
- Enter the invoice number, customer name, and invoice amount.
- Choose whether the due date should start from the invoice date or service date.
- Select the term type, then enter term days or a fixed due day.
- Add grace days if your billing policy gives extra settlement time.
- Choose calendar days or business days for counting the term.
- Apply a weekend and holiday rule when due dates must shift.
- Enter early payment discount days and rate if discounts are offered.
- Add a monthly late fee rate and reference date to analyze aging.
- Optionally list holiday dates that should be excluded or adjusted.
- Press submit to display the full result above the form.
- Use the export buttons to save the result as CSV or PDF.
Frequently asked questions
1. What does this calculator estimate?
It calculates the invoice due date, discount deadline, aging status, remaining days, overdue days, estimated late fees, and amount due based on your selected rules.
2. What is the difference between calendar and business days?
Calendar days count every date. Business days skip Saturdays, Sundays, and any holiday dates you enter in the holiday field.
3. When should I use the service date?
Use the service date when payment terms begin after delivery, completion, or another operational milestone instead of the invoice issue date.
4. What does modified following mean?
It moves the due date forward to the next business day, unless that shift enters a new month. Then it moves backward instead.
5. Can I calculate early payment discounts?
Yes. Enter discount days and a discount rate. The result shows the discount deadline, potential savings, and the reduced payable amount when eligible.
6. How is the late fee estimated?
The tool prorates the monthly late fee using overdue days divided by 30. It gives a planning estimate, not legal or contractual advice.
7. Why might the final due date differ from the provisional one?
A change happens when grace days are added or the selected weekend and holiday rule shifts the date to a valid business day.
8. Can this help with receivables aging reviews?
Yes. Use the reference date, discount window, and late fee settings to review settlement timing, current exposure, and collection priority.