GST VAT Calculator: Add, Remove and Reverse Tax on Any Price

GST vs VAT — What Is the Difference?

GST (Goods and Services Tax) and VAT (Value Added Tax) are functionally the same type of consumption tax — collected at each stage of the supply chain with the full burden ultimately borne by the end consumer. The name is the primary difference:

• GST countries: Australia, Canada, New Zealand, Singapore, India, Malaysia (SST), Gulf Cooperation Council (GCC) countries
• VAT countries: UK, EU member states, most of Europe, most of Africa, most of Asia, many Latin American countries
• Sales tax countries: US (state-level only, not federal; applies only at point of sale, not at each supply chain stage)

The calculation formulas for GST and VAT are identical. The conceptual difference is the mechanism: in a VAT/GST system, each business in the supply chain charges tax to its customer and receives input tax credits for tax paid to its suppliers. Only the final consumer has no mechanism to recover the tax — making it a consumption tax in effect, even though it is collected at every stage.

Standard Tax Rates by Country

How to Add Tax to a Price (Tax-Exclusive to Tax-Inclusive)

When a price is quoted excluding tax (ex-tax or net price), add tax to arrive at the consumer-facing total. This applies to B2B quotes, wholesale pricing, and any context where net prices are the norm.

Tax Amount = Net Price × (Tax Rate / 100)
Gross Price = Net Price + Tax Amount

Example: $200 net at 10% GST. Tax = $200 × 0.10 = $20. Gross = $200 + $20 = $220.

Simplified: Gross = Net × (1 + Tax Rate / 100) = $200 × 1.10 = $220.

How to Remove Tax from a Price (Reverse Calculation)

When a price already includes tax and you need to extract the net amount and tax component, the reverse formula is essential. This is used constantly for: reconciling receipts, extracting the GST or VAT portion for a tax return, and verifying that a quoted tax amount matches the gross total.

Net Price = Gross Price / (1 + Tax Rate / 100)
Tax Amount = Gross Price − Net Price

Example: $220 including 10% GST. Net = $220 / 1.10 = $200. Tax = $220 − $200 = $20.

Common mistake to avoid: taking 10% of the gross price directly gives $22, not $20. This is wrong — the 10% rate applies to the net amount, not the gross. The reverse formula is the only correct method.

How to Use the GST / VAT Calculator

1. Open the GST / VAT Calculator
2. Select Add Tax if your amount is net (before tax), or Remove Tax if your amount already includes tax
3. Enter the amount and either type a custom tax rate or click one of the preset buttons (5%, 7.5%, 10%, 12%, 15%, 18%, 20%, 25%)
4. Click Calculate to see the net amount, tax amount, and gross total with a visual net/tax proportion bar

Compound Taxes — GST + Provincial / State Tax

Some jurisdictions apply multiple tax layers. Canada is the most common example: each province has its own additional tax on top of the 5% federal GST:

Quebec's QST is calculated on the GST-inclusive price (a tax on a tax), which is why the combined rate is slightly higher than the arithmetic sum. For provinces with separate GST and PST, the calculator can be used twice — first to add GST, then to add PST to the GST-inclusive total.

Practical Use Cases

Invoicing and quoting

B2B invoices typically show prices ex-tax with the GST or VAT amount itemised separately. Use Add Tax mode to calculate the tax line and verify the invoice total before sending. For Australian businesses, a valid tax invoice must separately show the GST amount on invoices where the total including GST is $82.50 or more. Use the Invoice Generator to create properly formatted invoices with automatic tax calculation.

Reconciling receipts and expenses

When reimbursing employee expenses or preparing bookkeeping entries, you often need to extract the GST or VAT component from a tax-inclusive receipt total. Remove Tax mode splits the gross amount into net and tax components — essential for accurate journals and GST/VAT return preparation. For a $330 receipt including 10% GST: Net = $300, GST = $30.

Consumer price checking

If a retailer advertises a price ex-tax and you want to know the final consumer price, Add Tax mode gives you the total immediately. This is common for electronics, business software, and professional services where prices are often listed ex-tax for B2B audiences.

Pricing products for multiple markets

When selling across different jurisdictions with different VAT or GST rates, use the calculator to derive the gross consumer-facing price for each market from a single net wholesale price. A £100 net price becomes £120 at UK 20% VAT, €120 at EU 20% VAT, AU$110 at Australian 10% GST, and NZ$115 at New Zealand 15% GST — each calculated in Remove/Add Tax mode for the target market.

Validating supplier invoices

When receiving a supplier invoice, verify the arithmetic before approving payment. A common invoice error is calculating tax on a rounded subtotal, which produces a tax figure that does not match the gross total exactly. Enter the net amount and tax rate to confirm the stated tax and total are correct.

Tax Invoices vs Regular Invoices

In GST/VAT-registered jurisdictions, there is typically a distinction between a tax invoice (which includes the supplier's tax registration number and explicit tax amount) and a regular receipt. Only a valid tax invoice allows the recipient to claim an input tax credit on their own GST/VAT return. Key requirements for a tax invoice vary by jurisdiction but typically include:

• The word “Tax Invoice” clearly displayed
• Supplier's name, address, and tax registration number (ABN in Australia, GST number in NZ, VAT number in UK/EU)
• Issue date
• Description of the goods or services supplied
• GST or VAT amount stated separately (or a statement that all amounts are tax-inclusive)

Frequently Asked Questions

Why can't I just multiply the gross by the tax rate to get the tax amount?

Because the tax rate applies to the net amount, not the gross. If a $110 price includes 10% GST, the net is $100 and the tax is $10 — 10% of $100. Multiplying $110 by 10% gives $11, which overstates the tax by $1. The correct reverse formula is $110 / 1.10 = $100 net, and tax = $110 − $100 = $10.

What is the difference between zero-rated and exempt supplies?

Both result in no tax charged to the customer. Zero-rated supplies (e.g. most food exports and fresh food in Australia) allow the supplier to reclaim input tax credits paid on purchases related to those supplies. Exempt supplies (e.g. financial services, residential rent in many jurisdictions) do not allow input credit recovery. The distinction matters for GST/VAT return preparation but does not affect the customer-facing calculation.

Does this calculator handle compound taxes?

The calculator applies one rate at a time. For compound taxes — like Canada's GST plus provincial PST/QST — calculate the first tax, then use the resulting total as the input for the second tax. Quebec's QST is applied to the GST-inclusive amount, so: start with net, add 5% GST, then apply 9.975% QST to the GST-inclusive subtotal.

Can I use this for VAT returns?

The tool is useful for quickly verifying individual transaction amounts and extracting tax components from receipts. For complete VAT or GST return preparation, you need accounting software that accumulates all transactions across a return period. Always confirm figures with your accountant or tax adviser before filing.

What is the difference between inclusive and exclusive pricing?

Tax-exclusive pricing (ex-tax) shows the net amount before tax — the buyer pays the stated price plus tax on top. Tax-inclusive pricing (inc-tax, gross) shows the total the buyer pays — tax is already embedded. B2B transactions often use exclusive pricing; consumer retail typically uses inclusive pricing. The calculator handles both: Add Tax for exclusive-to-inclusive; Remove Tax for inclusive-to-exclusive.