Calculation Result
This summary appears after you submit the calculator.
| Period | Start | End | Opening Balance | Interest Added | Ending Balance |
|---|
Calculator Input
Use dates or manual days, then review totals and the accrual schedule.
Example Data Table
| Original Balance | Annual Rate | Method | Days Late | Penalty Rate | Fixed Penalty | Credits | Estimated Total Due |
|---|---|---|---|---|---|---|---|
| $3,500.00 | 8.50% | Daily Compounding | 90 | 2.50% | $35.00 | $100.00 | $3,596.62 |
| $6,200.00 | 7.25% | Simple Interest | 180 | 3.00% | $50.00 | $300.00 | $6,357.67 |
| $12,000.00 | 9.10% | Monthly Compounding | 365 | 1.50% | $75.00 | $500.00 | $12,892.90 |
Formula Used
Interest = Principal × Annual Rate × (Days Late ÷ 365)
Interest = Principal × [(1 + Annual Rate ÷ 365)Days Late − 1]
Interest = Principal × [(1 + Annual Rate ÷ 12)Months Late − 1]
Total Due = Principal + Interest + Percentage Penalty + Fixed Penalty − Credits
The calculator estimates months late with an average month length of 30.4375 days. Credits reduce the final balance after interest and penalties are added.
How to Use This Calculator
- Enter the original unpaid tax balance.
- Type the annual interest rate applied to the overdue balance.
- Choose simple, daily, monthly, or yearly interest treatment.
- Select date-based mode or manually enter the number of late days.
- Add optional percentage penalties, fixed penalties, and any payments or credits.
- Pick the currency symbol and preferred rounding precision.
- Press Calculate Interest to show totals above the form.
- Download a CSV summary or a PDF report for your records.
What This Tool Calculates
Days late Interest accrued Penalty estimate Credits applied Effective growth Schedule tableUse this estimate when comparing repayment timing, checking cash flow, or building a supporting worksheet before talking with a tax professional or revenue authority.
Frequently Asked Questions
1) Does this calculator replace an official agency notice?
No. It is a planning estimate. Agencies can change rates, use different daily factors, apply separate penalties, or round balances under their own rules.
2) Which interest method should I choose?
Choose the method that best matches the rule you are reviewing. If you are unsure, daily compounding is often the closest estimate for many real-world tax interest systems.
3) Can I calculate interest without dates?
Yes. Switch the late period input to manual mode and enter the total number of late days directly.
4) Are penalties included in the final total?
Yes. The final balance can include both a percentage penalty and a fixed penalty. Enter zero in either field if that charge does not apply.
5) How are credits handled here?
Credits and payments are subtracted from the ending balance after interest and penalties are estimated. That keeps the summary simple and easy to audit.
6) Why does the monthly method use estimated months?
The tool converts days into months using an average month length. That gives a consistent approximation when exact calendar-month compounding rules are unknown.
7) Can the total due become negative?
No. If credits exceed the estimated balance, the tool floors the total due at zero to avoid showing a negative amount owed.
8) What downloads are included?
You can export a CSV file containing the summary and schedule data. You can also generate a PDF report with the main result figures.