GST Interest Calculator
Understanding Your Results
Outstanding Amount
The original GST debt before interest. This is what you should have paid on the due date. This amount does not change - it's your base liability.
Interest Amount
The penalty charge for late payment, calculated daily from the due date. This is additional cost you must pay on top of the original GST. The longer you delay, the more interest accumulates.
Total Amount Due
The complete amount you must pay now, including both the original GST and accumulated interest. This is what you should pay to settle your GST liability in full.
What is GST Late Payment Interest?
Understanding GST interest charges and how they accumulate daily.
Real-World Examples
See how interest accumulates in different delay scenarios.
Australian Business - 1 Month Delay
A company paying GST 30 days late
Calculation Steps
- Outstanding: A$50,000
- Interest rate: 9.26% p.a.
- Days delayed: 30
- Daily rate: 9.26% ÷ 365 = 0.0254%
- Interest: A$50,000 × 0.000254 × 30 = A$381.37
Indian Company - Quarter Delay
A business paying GST 90 days late
Calculation Steps
- Outstanding: ₹200,000
- Interest rate: 18% p.a.
- Days delayed: 90
- Daily rate: 18% ÷ 365 = 0.0493%
- Interest: ₹200,000 × 0.000493 × 90 = ₹8,876.71
New Zealand Trader - 2 Weeks Late
A trader paying GST 14 days late
Calculation Steps
- Outstanding: NZ$15,000
- Interest rate: 8.22% p.a.
- Days delayed: 14
- Daily rate: 8.22% ÷ 365 = 0.0225%
- Interest: NZ$15,000 × 0.000225 × 14 = NZ$47.26
How to Use
Four simple steps to calculate GST late payment interest.
Select Country
Choose your country to load the official GST interest rate. The calculator automatically sets the current rate for your jurisdiction.
Enter Outstanding Amount
Type the GST amount you owe. This is the principal amount on which interest will be calculated.
Enter Days Delayed
Count days from due date to payment date (or today). Interest is calculated from the day after the due date.
View Interest
See daily rate, total interest, and amount due. The calculator shows the complete breakdown instantly.
Why Use This Calculator?
Key benefits of using our GST interest calculator for late payments.
Accurate Daily Calculation
Calculate interest precisely using daily rates, not monthly approximations. Get exact figures for tax compliance and financial planning.
Official Interest Rates
Pre-loaded with current official rates for Australia (9.26%), India (18%), New Zealand (8.22%), Canada (6%), and Singapore (5.5%).
Transparent Formula
See the complete calculation breakdown for audit and verification purposes. Understand exactly how interest is calculated.
Cost Planning
Estimate the true cost of delayed payment to make informed cash flow decisions and avoid unexpected charges.
Parameters Explained
Understanding each input field and how it affects your calculation.
Outstanding Amount
The GST amount you owe, before interest. This is the principal amount that should have been paid by the due date. Interest is calculated on this amount.
Days Delayed
Number of days from due date to payment date (or today). Count starts from the day after the due date. For example, if due date was January 1 and today is January 31, enter 30 days.
Annual Interest Rate
The yearly interest rate set by your tax authority. This is automatically loaded based on your country selection, but you can adjust it if rates have changed or for special circumstances.
Country
Determines the official interest rate and currency. Each country has different interest rates set by their tax authority for late GST payments.
Calculation Formulas
Mathematical formulas used to calculate GST interest
Daily Interest Rate
Convert the annual interest rate to a daily rate by dividing by 365 days. This gives you the interest rate per day.
Daily Rate = Annual Rate ÷ 365
Example: Annual: 10% → Daily: 10 ÷ 365 = 0.0274%
Interest Amount
Calculate the total interest by multiplying the principal by the daily rate (as a decimal) and the number of days. This is simple interest, not compounded.
Interest = Principal × (Annual Rate ÷ 365 ÷ 100) × Days
Example: Principal: $10,000, Rate: 10%, Days: 30 → Interest = $10,000 × 0.000274 × 30 = $82.19
Total Amount Due
Add the interest to the original outstanding amount to get the total you must pay. This is the complete amount due including accumulated interest.
Total = Principal + Interest
Example: Principal: $10,000, Interest: $82.19 → Total = $10,082.19
Common Questions
Answers to frequently asked questions about GST interest.
GST interest is calculated daily using the formula: Principal × (Annual Rate ÷ 365 ÷ 100) × Days. Each country sets its own annual interest rate. The interest starts accruing from the day after the due date and continues until payment is received.
Current rates: Australia 9.26%, India 18%, New Zealand 8.22%, Canada 6%, Singapore 5.5%. These rates are updated regularly but check official tax authority websites for the most current rates as they can change.
In most countries, GST interest is simple interest, not compounded. This calculator uses simple interest which is standard practice. The interest is calculated on the original outstanding amount only, not on accumulated interest.
Interest is calculated automatically by tax authorities based on the number of days delayed. The only way to reduce it is to pay the outstanding GST as soon as possible. Each day of delay adds more interest.
Yes, interest is charged from the day after the due date. Even one day delay incurs interest charges. While the amount may be small for short delays, it's still calculated and must be paid.
Disclaimer
This calculator provides estimates based on standard interest calculation formulas. Interest rates and policies may change. Always verify current rates with official tax authority sources. For tax advice specific to your situation, consult a qualified tax professional or accountant. We are not responsible for any decisions made based on this tool.