GST Calculation Worksheet
A GST Calculation Worksheet is a record used to summarise sales and purchases to determine the net GST payable or refundable on a Business Activity Statement. It is required under the A New Tax System Goods and Services Tax Act 1999 to substantiate figures reported to the ATO.
A tool to help businesses record sales and purchases to calculate the net Goods and Services Tax amount to report or claim on their Business Activity Statement.
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About this Document
A GST Calculation Worksheet is a vital working paper for any Australian business registered for Goods and Services Tax. It is not a form you send to the Australian Taxation Office. Instead, it is a record you keep to work out the numbers you need to fill in your Business Activity Statement. This document helps you summarise your total sales, total purchases and the amount of GST involved for a specific tax period. For tradespeople and small business owners, keeping accurate records is a legal requirement under the Taxation Administration Act 1953. This worksheet serves as the bridge between your daily receipts and your quarterly or monthly BAS. If the ATO audits your business, they will ask to see how you calculated your GST figures. This worksheet is the proof that your calculations are correct. The ATO requires you to keep records for five years. Using a worksheet makes this process easier and more accurate. This guide explains how to create and use this worksheet effectively. It covers the legal requirements, the specific tax codes you must use and common mistakes that lead to fines. The ATO uses the A New Tax System Goods and Services Tax Act 1999 to define what is taxable and what is not. You must understand the difference between a GST free sale, a taxable sale and an input taxed sale. A taxable sale includes GST. You charge this to your customers and pass it on to the ATO. A GST free sale does not include GST. Common examples include basic food, some medical services and some educational courses. Even though you do not charge GST on these items, you can still claim GST credits on the things you bought to run your business. Input taxed sales are different. You do not charge GST on them but you usually cannot claim GST credits for your purchases. Residential rent is a common example of an input taxed sale. Your worksheet must clearly separate these three types of sales. If you mix them up, you will pay the wrong amount of tax. The worksheet also handles purchases. You need to separate purchases that have GST from those that do not. Purchases with GST are called creditable acquisitions. You can claim back the GST portion as an input tax credit. Purchases without GST, such as bank fees or residential rent, do not give you a credit. You must list these separately on your worksheet. The GST Calculation Worksheet helps you calculate G1, the total sales on your BAS. It helps you calculate 1A, the total GST you owe on sales. It helps you calculate 1B, the total GST credits you claim on purchases. The difference between 1A and 1B is the amount you pay to the ATO or the amount they refund to you. Accuracy is critical. If you make a mistake, you may underpay tax and incur penalties. The ATO applies a failure to pay penalty and interest charges. If you overpay, you hurt your cash flow. You can use the accounting method that suits your business. This is called the cash method or the non cash method. The cash method works on the money actually coming in and going out of your bank account. The non cash method works on invoices you issue or receive. You must tell the ATO which method you use. Your worksheet should match that method. If you account on a cash basis, do not list invoices on your worksheet until the customer pays you. If you use a non cash basis, list the invoice on the worksheet on the date you issue it. Consistency is key. You cannot switch methods without permission from the ATO. For tradespeople, this worksheet is essential for managing job costs. When you quote a job, you must decide if the price includes GST. If the price is GST inclusive, you must divide the total by 11 to find the GST component. If the price is GST exclusive, you multiply by 0.1 to find the GST. The worksheet helps you track these amounts for every job. This ensures you do not spend the GST money collected from customers. That money belongs to the ATO. It is not part of your business profit. The worksheet also helps you manage private use deductions. If you buy tools or materials for your business but use them for personal projects, you cannot claim the full GST credit. You must adjust your claim based on the percentage of business use. Your worksheet should have a section to record these adjustments. The ATO provides a standard paper worksheet called the GST calculation worksheet for BAS. You can use this or create your own electronic version in Excel or accounting software. If you create your own, it must contain the same information as the ATO version. It must allow you to clearly distinguish between GST free, input taxed and taxable supplies. It must show total sales, total GST on sales, total purchases and total GST on purchases. You must sign and date the worksheet when you finish it. This creates a formal record of your work. In the event of an audit, a signed worksheet is strong evidence that you have taken reasonable care. The ATO may remit penalties if they see you have good records and tried to follow the law. However, they will not accept ignorance as an excuse. Every business owner is responsible for understanding their GST obligations. This guide is a starting point but you should seek advice from a registered tax agent if you are unsure. The interaction between GST and other taxes can be complex. For example, the Wine Equalisation Tax and Luxury Car Tax have specific rules. Fuel tax credits also interact with GST. Your worksheet should include fields for these adjustments if they apply to you. Records must be in English or a form that the ATO can access and understand. Electronic records are acceptable but must be secure and backed up. You must be able to produce them quickly if asked. Using a spreadsheet formula reduces the risk of calculation errors. Formulas ensure that totals add up correctly every time. Check your formulas regularly to make sure they are still working. A common mistake is manually typing over a formula and breaking it. Another mistake is failing to reconcile the worksheet totals to your bank statements and accounting software. If the numbers do not match, you have missed something. You must find the difference before you lodge your BAS. The Bas returns are due monthly, quarterly or annually. Most small businesses lodge quarterly. The due dates are the 28th of the month following the end of the quarter. If you use a tax agent, you may have longer to lodge. Your worksheet should be completed before this due date. This gives you time to review the numbers and ask questions. The worksheet also helps you prepare cash flow forecasts. By knowing how much GST you owe, you can set aside the right amount of money. This prevents a shock when the BAS payment is due. Good cash flow management is for tradespeople who deal with seasonal work and long payment terms. The GST rate in Australia is ten percent. This is fixed by law. You must not charge a different rate unless a specific concession applies. Some things are not subject to GST. You must identify these correctly. If you run a medical practice or an educational institution, you need to be very careful with your classifications. The ATO publishes detailed guides on these industries. Read the guides that apply to your business. Use the worksheet to test your understanding. If you are unsure if a sale is taxable, treat it as taxable and seek advice. It is better to overpay and get a refund later than to underpay and face penalties. The worksheet is also useful for the annual GST return or review. If you report quarterly, the ATO may send you an annual GST information report. This shows the total GST you reported during the financial year. You should compare this to your yearly worksheets. Any large differences need to be investigated. The ATO uses data matching to check your figures. They compare your BAS data against the data reported by your suppliers and customers. If you report sales that do not match your supplier purchases, the ATO may flag your account for review. Your worksheet helps you explain these differences. It provides the audit trail you need to prove your income and expenses. In conclusion, the GST Calculation Worksheet is a mandatory part of good business administration. It ensures you comply with the A New Tax System Goods and Services Tax Act 1999 and the Taxation Administration Act 1953. It protects you in an audit and helps you manage your cash flow. Take the time to set it up correctly and use it for every reporting period. It is one of the best tools you have to manage your tax obligations.
Key Facts
- You must keep GST records for five years as required by the Taxation Administration Act 1953.— Taxation Administration Act 1953 (Cth)
- Businesses with a turnover of $75,000 or more must register for GST.— A New Tax System Goods and Services Tax Act 1999 (Cth)
- The current GST rate in Australia is 10%.— A New Tax System Goods and Services Tax Act 1999 (Cth)
- You can claim GST credits for purchases used solely for business purposes.— A New Tax System Goods and Services Tax Act 1999 (Cth)
- BAS lodgement is usually due quarterly by the 28th of the month following the quarter end.— Australian Taxation Office (ATO)
Sources
Required Sections
Business Details
Identification of the business and the reporting period.
Business Details
Enter the official legal name of your business exactly as it appears on your Australian Business Register (ABR) record. This must match the name associated with your ABN. Providing the correct legal name ensures the Australian Taxation Office (ATO) can accurately match your Business Activity Statement (BAS) to your tax account. If you operate as a sole trader using your personal name, enter your full name here.
Australian Business Number (ABN)
Record your 11-digit ABN in this field. It is a legal requirement under the A New Tax System (Australian Business Number) Act 1999 to hold an active ABN to claim GST credits. Before you start this worksheet, verify your ABN is still active on the Australian Business Register website. An inactive ABN will prevent you from reporting and claiming GST correctly.
Tax Period
Enter the start and end dates for the specific reporting period covered by this worksheet. This might be a month, a quarter, or a financial year ending on 30 June. Accurate dates are essential for determining when tax obligations arise under the Income Tax Assessment Act 1997 and GST law.
You must report on the same cycle as your GST registration. For example, if you report quarterly, your period will align with the standard quarterly cycles used by the ATO, such as 1 July to 30 September. Ensure the dates are complete and include the day, month, and year to avoid confusion.
Basis of Accounting (Cash or Non-Cash)
You must select the accounting method your business uses to calculate GST. The ATO allows two main methods.
Cash basis You account for GST when you receive payment for your sales and when you actually pay for your purchases. Most small businesses with a turnover of less than $10 million use this method. It is often preferred by tradespeople because GST is only payable on money that has actually hit your bank account. If you have not yet received payment from a customer, you do not report the GST on that invoice yet.
Non-cash basis (accruals) You account for GST when you issue an invoice for your sales or receive an invoice for your purchases, regardless of when money changes hands. This method is mandatory if your GST turnover is $20 million or more, but it can be voluntarily used by smaller businesses. Under this method, if you send an invoice in late June but do not get paid until July, you must still report the GST for the June period.
Refer to Taxation Ruling TR 2008/2 regarding the time of supply for more detailed guidance. Select the one basis that applies to your entire business for this period. You cannot mix methods for different transactions unless specific approval is granted by the ATO.
Total Sales (G1)
Record of all income made during the period.
Total Sales (G1)
Use the table below to record all sales you made during the reporting period. You must separate your sales into three categories based on their GST treatment. This separation is required under A New Tax System (Goods and Services Tax) Act 1999. Getting these numbers right ensures you pay the correct amount of GST and claim the right credits.
How to use the table
| Type of Sale | Description | Total Amount ($) |
|---|---|---|
| GST-free sales | Input the total value of sales that do not include GST. Examples include basic food, medical exports, and some educational courses. | __________ |
| Input taxed sales | Input the total value of supplies where you do not charge GST and cannot claim credits. Examples include residential rent and most financial supplies. | __________ |
| Taxable sales | Input the total value of sales that include GST. This is the standard rate for most goods and services. | __________ |
| Total Sales (G1) | Add the three amounts above. This total must equal the figure you write at label G1 on your Business Activity Statement. | __________ |
Important notes for completion
For label G1, you must report the total price of the sale, not just the net amount. If you charge GST on a sale, you include the GST component in the total. If you make a sale that is a mix of taxable and GST-free items, you must split the value based on the actual price of each item.
Do not include GST in the total if the sale is GST-free. You only include the GST amount in the total for taxable sales. If you are not registered for GST, report your total sales at G1 but leave G2 and G3 blank.
Legislative reference
You report these figures to satisfy your obligations under A New Tax System (Goods and Services Tax) Act 1999. The Australian Taxation Office uses this data to reconcile your business activity against the information provided by your suppliers and customers.
GST on Sales (1A)
Calculation of the tax owed on sales.
This section calculates the total Goods and Services Tax (GST) you must pay to the Australian Taxation Office (ATO) for the reporting period. Label this total at 1A on your Business Activity Statement (BAS). Getting this figure right ensures you do not overpay tax or incur penalties for underpayment.
GST on Taxable Sales
Start by entering the total GST amount for all sales and income that included tax. You calculate this based on the tax invoices you issued to customers.
- Standard rate (10%): Most sales of goods, services, and other things in Australia are taxable. If the total price of the job or sale is $110, the GST component is $10.
- GST-free sales: Do not include GST here. Basic food, some medical and health services, and some educational courses are GST-free. If you are a plumber, electrician, or builder, most of your sales will be taxable, but you must check if specific supplies qualify for an exemption.
- Input taxed sales: Do not include GST here. If you provide financial supplies or residential rent, you do not charge GST. You generally cannot claim GST credits on expenses related to these sales.
You must keep records for five years under Section 262A of the Income Tax Assessment Act 1936. Your tax invoices must meet the requirements of the A New Tax System (Goods and Services Tax) Act 1999 (GST Act).
Adjustments and Increasing Adjustments
You must add specific amounts to your GST payable if certain events occur. These are called increasing adjustments.
- Bad debts: If you wrote off a debt as bad in a previous period and claimed a GST credit, you must pay that GST back if you later recover the money. For example, if a customer pays an invoice you previously wrote off, you must include the GST portion of that payment in this section. This adjustment is required by Division 21 of the GST Act.
- Change of use: If you purchased an item for private use and claimed no GST credit, but later started using it for business in a way that attracts GST, you must account for the change. Conversely, if you purchase a business asset for creditable purposes but later use it privately, you may need to make an adjustment.
- Periodic adjustments: Some businesses use a method that accounts for changes in the extent of creditable purpose over a tax period.
Total GST on Sales (1A)
Add the GST calculated on your taxable sales to the total of any increasing adjustments. Write the final amount at 1A.
Ensure you follow the Taxation Administration Act 1953 regarding the accuracy of your return. If you make a mistake or leave something out, the ATO may apply a shortfall interest charge or penalties. Review your figures against your accounting software records before lodging.
Total Purchases (G10)
Record of all business expenses.
Non-creditable Purchases, Capital Acquisitions and Other Creditable Acquisitions
Use this section to record the total amount of purchases for your business. You must complete this table to calculate label G10 on your Activity Statement. The total purchases figure represents the total spending for your business before subtracting any non-creditable amounts.
You must distinguish between three types of purchases.
1. Non-creditable purchases These are expenses where you cannot claim a GST credit. You should include the total GST-inclusive amount here. Common examples for tradespeople include expenses with no GST in the price, input taxed supplies, and private expenses.
Under A New Tax System (Goods and Services Tax) Act 1999, you cannot claim credits for GST-free purchases, such as basic medical expenses or some educational courses. You also cannot claim credits for input taxed supplies like residential rent or interest charges. If you operate as a sole trader, you must also exclude private expenses like groceries or personal fuel usage from your claimable credits. Record these private costs in the non-creditable column to ensure your total spending is accurate but your GST claim is not inflated.
2. Capital acquisitions Capital purchases are significant assets you buy for your business. You must record the total cost of these assets here. For a tradesperson, this includes new utes, tools, machinery, or office equipment. You should only record capital acquisitions in the period you paid the invoice or received a tax invoice. You must hold a valid tax invoice for purchases over $1,000 to claim a credit.
3. Other creditable acquisitions These are standard day-to-day business expenses where you paid GST and can claim it back. This includes timber, steel, fuel, safety gear and trade supplies. Record the total GST-inclusive amount here. You must ensure the expense relates directly to your business activities.
Table for Calculating Total Purchases
| Description | Total Purchases (a) |
|---|---|
| Non-creditable purchases | $ __________ |
| Capital acquisitions | $ __________ |
| Other creditable acquisitions | $ __________ |
| Total purchases (G10) | $ __________ |
Add the amounts from column (a) to calculate the Total purchases amount. Transfer this final figure to label G10 on your Activity Statement. The Australian Taxation Office uses this figure to reconcile your business activity. Ensure the total at label G10 matches your accounting software records or cashbook summaries for the reporting period.
GST on Purchases (1B)
Calculation of tax credits on expenses.
GST on Purchases (1B)
You must calculate the total GST credits you can claim for your business purchases. This total goes at label 1B on your Business Activity Statement (BAS). You can only claim a credit for GST included in the price of things you buy for your business. This is often called an input tax credit under the A New Tax System (Goods and Services Tax) Act 1999.
You need to separate your purchases into two main groups, capital items and other items.
Capital Items
Capital items are significant assets you buy for your business, such as a new ute, heavy machinery, tools, or office equipment. You must calculate the total GST paid on these purchases.
- Full Credit: If you use the asset 100% for business, you claim the full GST amount (usually one eleventh of the total price).
- Private Use: If you use the asset for private reasons, you must reduce your claim. For example, if you use a work ute for personal trips on weekends, you must adjust the credit based on the percentage of business use.
Other Items
This section covers your day-to-day business expenses. This includes materials, fuel, trade supplies, protective gear, and accounting fees.
- Check your tax invoices.
- Identify the total GST amount included in these purchases.
- Add these figures together to get your total GST credits for other items.
Private Use and Adjustments
You must not claim GST credits for anything used for private purposes. If you buy something for both business and private use, you must apportion the credit. You calculate this based on your actual business use percentage.
Common adjustments include:
- Private use of business vehicles.
- Goods taken from your business trading stock for personal use.
- Entertainment expenses where there is no private fringe benefit tax exemption.
If your private use changes during the tax period, or if you stop using a business asset for private purposes, you may need to make a further adjustment. You must keep accurate records to prove your business use percentage if the Australian Taxation Office (ATO) asks.
Total GST on Purchases (1B)
Add the GST credits from capital items and other items. Then subtract any adjustments for private use.
- (GST on Capital Items) + (GST on Other Items) - (Private Use Adjustments) = Total at label 1B.
Ensure the records you keep satisfy the requirements of the Taxation Administration Act 1953. You must hold a valid tax invoice for purchases over $82.50 (including GST) to claim a credit.
Net GST Calculation
Final amount owed or refundable.
Net GST Calculation
This section determines the final amount you owe to the Australian Taxation Office (ATO) or the amount the ATO refunds to you. You must finalise this figure after completing your calculation for Total GST on Sales (Label 1A) and Total GST on Purchases (Label 1B).
Calculating the Net Amount
To find your net GST, subtract the total tax credits on your business purchases from the total tax collected on your sales.
The formula is simple:
- Label 1A (Total GST on Sales) minus Label 1B (Total GST on Purchases) equals Net GST.
Scenario 1: You owe money If Label 1A is larger than Label 1B, the result is a positive number. This means you collected more GST from your customers than you paid on your business expenses. You must pay this difference to the ATO by the due date listed on your Business Activity Statement (BAS).
Scenario 2: You receive a refund If Label 1B is larger than Label 1A, the result is a negative number. This means the GST credits on your purchases exceed the GST you collected. You are entitled to a refund. The ATO will generally pay this amount directly into your nominated bank account.
Legal Framework
The requirement to calculate and report this net amount comes from A New Tax System (Goods and Services Tax) Act 1999. Under Division 7 of that Act, you are liable for the net amount for each tax period. Section 17-5 specifically states that your net amount is the sum of your GST payable on sales minus your input tax credits.
Ensuring Accuracy
Mistakes in this final calculation can lead to penalties or interest charges under the Taxation Administration Act 1953. Before you finalise the figure, double-check that you have included every transaction.
- Verify that you claimed credits for all business expenses, including minor cash purchases.
- Ensure you did not claim GST on items that are input taxed, such as some financial supplies or residential rent.
- Check that you correctly classified purchases between private and business use. You can only claim a credit for the portion used for business purposes.
Record Keeping
You must keep records for five years that substantiate how you calculated this final net figure. Your records should show the working papers that link the totals in Label 1A and Label 1B back to your original invoices and receipts. If the ATO reviews your return, they will look for evidence that the subtraction was performed correctly and matches your ledger data.
Frequently Asked Questions
What is a GST Calculation Worksheet?
When do I need a GST Calculation Worksheet?
Is a GST Calculation Worksheet legally required in Australia?
How do I calculate GST on a total amount?
Can I claim GST credits on all my business purchases?
Do I need a worksheet if I use accounting software?
What is the difference between G1 and 1A on the worksheet?
How long must I keep my GST Calculation Worksheets?
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