Business · Calculator companion · By K Imports
Invoice late-payment interest: practical guide
This guide explains how to use the Count.ie invoice late-payment interest. Calculate simple overdue interest using the applicable entered rate and compensation. Follow the inputs, method and worked example below, then compare your own scenario.
Guide written .
Open the Invoice late-payment interest calculatorWhat to prepare
- Gather supplier quotes, invoices, time records and the actual scope of the job or business decision.
- Separate revenue from VAT, direct costs from overheads, and profit from the timing of cash receipts.
- Use the same accounting period and currency for related inputs.
Understand the inputs
- Applicable annual interest rate (%)
- Enter the rate applicable to your agreement and period; no statutory rate is preset.
- Applicable fixed compensation (€)
- Enter only compensation to which you are entitled.
The calculation method
Simple interest = outstanding principal × entered annual rate × days overdue ÷ 365; entered compensation is added.
Worked example
Illustrative inputs and their result.
Example inputs
- Original invoice principal (€)
- 5000
- Applicable annual interest rate (%)
- 0
- Days overdue
- 60
- Applicable fixed compensation (€)
- 0
- Payments already received (€)
- 0
Calculated example result
- Late Interest
- €0.00
- Outstanding Principal
- €5,000.00
- Total Due
- €5,000.00
How to interpret the result
A profitable estimate can still create a cash shortfall. Read the cost and timing assumptions as well as the headline profit, price or return; the result is a scenario, not a sales forecast.
Keep the scope constant while changing price, volume, supplier cost or time. A lower-sales or higher-cost case helps show whether the decision depends on an optimistic assumption.
Common mistakes to avoid
- Do not confuse markup on cost with margin on selling price.
- Include work that is easy to miss, such as travel, setup, rework and administration, where the model supports it.
- Do not treat tax collected or an unpaid invoice as freely available cash.
Assumptions and sources
This arithmetic does not determine legal entitlement. Part-period payments require separate period calculations.
If your case falls outside this scope, use a more suitable calculator or contact us about an unclear method.