GST Late Fee / Penalty Calculator
Estimate late fees and interest when a GST return is filed after the due date. Use this for planning and quick checks — always confirm with current official rules.
When filings are late, fees and interest can add up. This calculator is intended as a quick estimate so you can plan payments, understand impact, and compare scenarios.
Need to calculate GST amounts first? Use the GST calculator.
How to estimate late fee and interest
Enter dates and amounts, then review the estimate.
1. Enter due and filing dates
The time gap drives late fee/interest in most scenarios.
2. Enter relevant amounts
Provide the values your scenario requires to estimate interest.
3. Compare scenarios
Try different filing dates to understand impact.
Where it helps
Rough late fee estimate
Estimate late fees for planning and quick checks when a return is filed after due date.
Interest planning
Get a sense of interest impact based on the inputs you provide.
Scenario comparison
Compare two filing dates to see how time affects late fee and interest.
Internal reporting
Useful for creating a quick summary for internal follow-ups and reminders.
Common pitfalls
Rules change and can vary
Late fee and interest rules can change with notifications. Use this as an estimate and confirm with the latest rules.
Return type differences
Some return types can have different treatments. Make sure you choose the correct return scenario in the tool.
Partial payments and adjustments
If you have partial payments, credits, or adjustments, the real payable may differ from a simple estimate.
Rounding and period boundaries
Depending on how you round and which period you apply, your accounting system may show slightly different numbers.
What this tool supports
| Feature | Supported | Notes |
|---|---|---|
| Late fee estimate | Yes | For planning and checks. |
| Interest estimate | Yes | Based on the inputs you provide. |
| Scenario comparison | Yes | Try different filing dates. |
| Official filing | No | Use official rules for final payable amounts. |
Frequently Asked Questions
User reviews
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Need a quick estimate?
Enter your dates and scenario amounts to estimate late fee and interest.