BAS Calculator Australia

A Business Activity Statement (BAS) is a form submitted to the ATO to report and pay several tax obligations including GST, PAYG withholding, PAYG instalments, and other taxes. Most small businesses lodge BAS quarterly.

Quarterly BAS is due 28 days after the end of each quarter: 28 October (Q1), 28 February (Q2), 28 April (Q3), and 28 July (Q4). Q2 is already pushed out to 28 February for the Christmas and New Year period. If you lodge the statement online yourself, through Online services for business, the ATO app, myGov or SBR-enabled software, the ATO's two week lodgment concession gives you an extra fortnight to lodge and pay quarters 1, 3 and 4: 11 November, 12 May and 11 August. Quarter 2 gets no concession because its due date is already extended. A registered tax or BAS agent gets 25 November, 26 May and 25 August. When a due date falls on a weekend or public holiday you can lodge and pay on the next business day.

GST turnover under $20 million: you generally report quarterly (the default for most small businesses), with the option to report monthly. GST turnover of $20 million or more: monthly reporting is compulsory. Some businesses report annually if voluntarily registered and turnover is under the $75,000 ($150,000 non-profit) registration threshold. Always confirm your cycle on your ATO Online Services dashboard.

Label 1A is the GST on sales, the total GST you've collected from customers. Label 1B is the GST on purchases, the GST you've paid on business purchases. The difference (1A minus 1B) is your net GST payable to the ATO, or refundable if 1B exceeds 1A.

Because 1A is GST on your taxable sales, not on everything at G1. G1 is total sales including GST, and three slices of it carry no GST: exports at G2, other GST-free sales at G3 (basic food, most health and education), and input-taxed sales at G4 (residential rent and financial supplies). The ATO worksheet adds those three into G5, takes G5 off G1 to get G6, and divides G6 by 11. A cafe with $50,000 at G1 and $8,000 of GST-free basic food reports $3,818.18 at 1A, not $4,545.45. Dividing G1 by 11 overstates the GST you owe.

Everything you sell goes in G1, which is why G1 is larger than the figure 1A is worked out from. Exports of goods and most services supplied to customers outside Australia go in G2. GST-free sales go in G3: most basic food, most health and medical services, most education courses, childcare, and eligible sales of a going concern. Input-taxed sales, such as residential rent and financial supplies, go in G4. All three come out of G1 before 1A is calculated, so none of them adds GST to what you owe. G4 is not a box on the BAS form itself, but the worksheet still needs it, and leaving it out is the single most expensive mistake a residential landlord can make on this statement.

Rent from residential premises and financial supplies (interest, most bank and lending income) are input taxed. You charge no GST on them, and you claim no GST credits on what you buy to make them. On the ATO GST calculation worksheet they sit at G4, inside G1 but subtracted again at G5, so they never reach 1A. The purchases side mirrors it: repairs, agent fees and other costs of producing those sales go at G13 and are subtracted before 1B. A landlord with $60,000 of residential rent and $20,000 of taxable sales has G1 of $80,000, G4 of $60,000 and 1A of $1,818.18. Treating the whole $80,000 as taxable would report $7,272.73, an overstatement of $5,454.55 for one quarter.

Only if you are a small withholder, meaning you withhold $25,000 or less across the financial year. Small withholders report and pay PAYG withholding on the quarterly BAS. Medium withholders, from $25,001 to $1 million a year, report and pay monthly on an instalment activity statement, so their quarterly BAS carries GST and instalments but not three months of withholding. Large withholders, above $1 million, pay electronically within six to eight days of each withholding event. The ATO moves you between cycles and writes to you when it does. If you are not a small withholder, leave the W2 field on this page at zero.

PAYG instalments are pre-payments of your expected income tax. The ATO calculates an instalment amount or rate based on your most recent tax return. This is separate from PAYG withholding (tax withheld from employee wages).

No. The ATO asks for whole dollar amounts, with the cents left out and no rounding up to the next dollar, so $4,545.45 at label 1A is keyed as $4,545. That is why an estimate carrying cents can never match the statement you lodge, and why 1A, 1B and the total can each drift by up to a dollar against your accounting software. This page shows both: the exact figure, and the whole dollar figure to key onto the form. Round each label down on its own rather than rounding the total, because that is the order the form works in.

Four reasons account for almost every gap. Your software rounds each label down to whole dollars and this page shows cents. Your software knows the GST treatment of every individual line, while this page takes your totals on trust, so a sale coded GST-free in one and not the other moves 1A. Your software applies adjustments this page excludes: bad debts written off, credit notes, a change in creditable purpose (labels G7 and G18), fuel tax credits, wine equalisation tax and luxury car tax. And cash versus accruals decides which quarter a transaction falls in. Treat this page as a sanity check on the order of magnitude, and lodge from your books.

Yes, and it is a common source of a surprise bill. On a cash basis you account for GST in the period you are actually paid, and claim credits in the period you actually pay. On an accruals (non-cash) basis you account for GST in the period you issue or receive the invoice, whether or not the money has moved, so an invoice raised on 29 June and paid in August belongs to the June quarter. Businesses with GST turnover under $10 million can choose cash; above that, accruals is generally required. Whichever you use, use it consistently, and enter the totals for that basis here.

You have two routes. A credit error, where you paid too much GST, can be corrected on a later activity statement with no value limit, within the four year period of review. A debit error, where you paid too little, can also be corrected on a later statement if it is inside the ATO's limits: for GST turnover under $20 million that is an error value under $10,000, corrected on a statement lodged within 18 months of the original due date. Outside those limits, or where the error came from recklessness or disregard of the law, revise the original statement instead. Revising voluntarily generally reduces any penalty.

Yes, if you're registered for GST, you must lodge a BAS even if you have no sales or purchases for the period. Lodge a 'nil' BAS to avoid penalties.

You can lodge it yourself through ATO Online Services for business (sole traders can use the ATO app or myGov), by mail, or directly from SBR-enabled accounting software. Lodging online yourself earns the two week lodgment concession on quarters 1, 3 and 4, so self-lodging is not the slower path it is often described as. A registered BAS or tax agent can prepare and lodge on your behalf and has a slightly later program date again. Whichever channel you use, keep the records behind every label for five years.

The ATO can apply a failure-to-lodge penalty, calculated in penalty units for each 28-day period the statement is overdue (up to a maximum of five periods), and general interest charge accrues on any unpaid amount. If you can't pay in full, lodge on time anyway: lodging and paying are separate obligations, and the ATO offers payment plans for businesses that engage early.

W1 is the total of salary, wages, and other payments subject to PAYG withholding for the period, before any tax is taken out. W2 is the tax you actually withheld from those payments. Both come straight from your payroll records: W1 is the gross figure, W2 is the withheld tax you pass on to the ATO.

Simpler BAS is the default GST reporting method for businesses with GST turnover under $10 million. You only report three GST labels: G1 (total sales), 1A (GST on sales), and 1B (GST on purchases). Labels G2, G3, G10 and G11 no longer need to be reported to the ATO, and G4, G13, G14 and G15 never appeared on the form. All of them still decide what 1A and 1B come to, which is why this calculator asks for them and keeps them in your own records.