Add or remove GST in one click

To add 10% GST to an ex-GST price, multiply by 1.10. Example: $250 ex-GST × 1.10 = $275 GST-inclusive. The GST amount is $25. Quick formula: GST amount = Ex-GST price × 0.10. Most Australian businesses are required to register for GST if their annual turnover exceeds $75,000. Once registered, you charge GST on taxable supplies and can claim GST credits on business purchases.

To extract the GST from a GST-inclusive price, divide by 1.10 to get the ex-GST amount, then subtract to find the GST component. Example: $275 ÷ 1.10 = $250 (ex-GST). GST = $275 − $250 = $25. Never simply multiply by 0.10 on the inclusive price — that gives you 10% of the total, not the correct GST amount. The correct fraction to extract GST from an inclusive price is 1/11 (or dividing by 11): $275 ÷ 11 = $25.

Many essential items are GST-free (zero-rated): basic food items (fresh fruit, vegetables, bread, milk, meat, fish), medical services and medicines, most health services, educational courses, exports, and water. These are different from 'exempt' supplies. Input taxed supplies (like residential rent and financial services) also don't attract GST, but you can't claim GST credits for related business costs. Always check the ATO website for current GST-free lists as rules can be complex.

GST-registered businesses collect GST on their sales (output tax) and can claim back GST paid on business purchases (input tax credits). The difference is remitted to the ATO, typically quarterly via a Business Activity Statement (BAS). For example: you sell $1,100 (inc. GST), collecting $100 GST. You purchase $550 (inc. GST) of business supplies, paying $50 GST. Net GST payable to ATO = $100 − $50 = $50. This system means GST is effectively only paid by the end consumer.