Accountants Late Payment Interest (Hourly) Calculator Examples
Worked examples showing how overdue time, invoice value, and annual rate affect estimated late payment interest.
These examples use simple interest, a 365-day year, and hourly accrual. They illustrate how the same method can be applied to short delays, longer delays, and larger unpaid accountancy invoices.
Short delay on a small invoice
A £500 accountancy invoice is subject to an annual simple interest rate of 8%.
Input Summary
Invoice balance
£500
Annual rate
8%
Overdue period
2 days, 6 hours
Calculation Breakdown
- 1Convert time to hours(2 * 24) + 654 hours
- 2Calculate interest500 * (8 / 100) / 365 / 24 * 54£0.49
Result Summary
Calculate interest
£0.49
Accountants Late Payment Interest (Hourly) Calculator
Estimated interest is £0.49, making the estimated total due £500.49.
Thirty-day standard overdue invoice
A £1,000 accountancy invoice is overdue for 30 complete days at 8% per year.
Input Summary
Invoice balance
£1,000
Annual rate
8%
Overdue period
30 days
Calculation Breakdown
- 1Convert time to hours30 * 24720 hours
- 2Calculate interest1000 * (8 / 100) / 365 / 24 * 720£6.58
Result Summary
Calculate interest
£6.58
Accountants Late Payment Interest (Hourly) Calculator
Estimated interest is £6.58 and the estimated total due is £1,006.58.
Larger invoice overdue for 45 days and 12 hours
A £12,500 invoice is overdue at an annual simple rate of 10%.
Input Summary
Invoice balance
£12,500
Annual rate
10%
Overdue period
45 days, 12 hours
Calculation Breakdown
- 1Convert time to hours(45 * 24) + 121,092 hours
- 2Calculate interest12500 * (10 / 100) / 365 / 24 * 1092£154.11
Result Summary
Calculate interest
£154.11
Accountants Late Payment Interest (Hourly) Calculator
Estimated interest is £154.11, making the estimated total due £12,654.11.
How to Read Your Results
Late payment interest is the estimated interest accrued over the entered overdue period.
Total amount due is the unpaid invoice amount plus estimated interest only.
The hourly rate is derived from the annual rate using 365 days and 24 hours per day.
Round displayed currency amounts only after completing the calculation.
If the balance changed, calculate each balance period separately and add the results.
Assumptions & Important Notes
- All examples use simple interest.
- The annual rate remains unchanged throughout the overdue period.
- No partial payments, fixed charges, recovery costs, or tax adjustments apply.
- The rate is converted using a 365-day year.
Related Examples
Frequently Asked Questions
Can I enter days and extra hours together?
Yes. Enter full days and then add only the additional hours from zero to 23.
Why can two invoices with the same rate have different interest?
Interest depends on both the unpaid balance and the precise time overdue.
Are example results legally binding?
No. They are educational estimates based on the stated assumptions.
Should interest be rounded each day?
This calculator calculates the full period before displaying a rounded currency result. Other methods may round differently.
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