BAS and GST for tradies: a simple quarterly routine

Most tradies don’t mind the work. It’s the paperwork that wears them down, and BAS is the paperwork that turns up every three months whether you’re ready or not.

This guide covers what GST and BAS mean for a tradie in plain English: when you have to register, how GST works on your quotes and invoices, the due dates, and a routine that makes quarter end a one hour job instead of a weekend. Facts are from the ATO and business.gov.au, checked in October 2026. It’s general information, not tax advice. If you’re unsure about anything, a registered tax or BAS agent can look at your situation.

If you haven’t set up yet, start with our guide to setting up as a sole trader tradie, which covers your ABN and registrations in order.

GST in one paragraph

GST is a 10% tax on most goods and services sold in Australia. If you’re registered, you add GST to your taxable sales, collect it from customers, and pay it to the ATO. You also claim credits for the GST included in things you buy for the business, such as materials, fuel and tools. Your BAS is where those two figures meet: GST collected minus GST credits equals what you pay (or get back).

When you must register for GST

The ATO says you must register for GST within 21 days of your GST turnover reaching $75,000 or more. GST turnover is your total business income (not profit), measured two ways:

• Current: this month plus the previous 11 months.
• Projected: this month plus the next 11 months, if you expect to reach $75,000.

Either one triggers the requirement. If you register late, the ATO can backdate your registration, which means GST you didn’t charge customers may still be owed. You can also register voluntarily below the threshold. Some tradies do because builders and commercial clients expect GST invoices, and because they can then claim GST credits on tools and materials. Whether that suits you is a question for your tax agent.

Tax invoices: what to include

For taxable sales over $82.50 including GST, you must give a tax invoice if the customer asks for one. In practice, most tradies issue one for every job. For sales under $1,000, the ATO says a tax invoice must show:

• that it’s a tax invoice
• your name or business name, and your ABN
• the date it was issued
• a description of what you supplied, including quantity and price
• the GST amount, or a statement that the total price includes GST

Invoices of $1,000 or more must also show the buyer’s identity or ABN. Any decent invoicing app fills all of this in automatically. Our guide to invoicing and quoting apps compares the options.

BAS: how often and when

Your BAS reports GST and, if they apply to you, PAYG instalments and PAYG withholding for employees. Most small businesses report quarterly. The ATO says you must report monthly only if your GST turnover is $20 million or more, or the ATO tells you to.

Swipe the table sideways to see every column

A few points from the ATO worth knowing:

• Lodging online may give you an extra two weeks to lodge and pay quarterly BAS, except for Q2, which already includes a one month extension.
• Registered tax and BAS agents may have different, sometimes later, due dates for their clients.
• Weekends and public holidays move the due date to the next business day.
• If you voluntarily registered for GST and your turnover is under $75,000, you may be able to report annually instead.

If you can’t pay on time, contact the ATO or your agent before the due date. The ATO says payment plans may be available for debts of $200,000 or less through its online services, though general interest charge keeps adding up.

Cash or accrual

You can account for GST on a cash basis (when you’re paid and when you pay) or an accrual basis (when you invoice and when you’re invoiced), if you’re eligible. Many small trade businesses use cash basis because GST only becomes payable once the customer has actually paid. Check eligibility with the ATO or your agent, and set it correctly in your accounting software.

A simple weekly and quarterly routine

The tradies who find BAS easy aren’t better at tax. They just don’t leave it for three months.

Every week (15 minutes):

1. Photograph receipts in your accounting app’s receipt capture, or forward them to it.
2. Reconcile the bank feed: match each transaction to an invoice or a bill.
3. Chase any invoice that’s overdue.
4. Move a set percentage of every payment received into a separate tax account. That covers the GST you’ve collected, plus a buffer for income tax.

At quarter end (about an hour):

1. Check every bank transaction for the quarter is reconciled.
2. Look for purchases with no GST that should have it, or the reverse. Bank fees, insurance stamp duty and some overseas software are common traps.
3. Run the GST or BAS report in your software and compare it with last quarter.
4. Lodge through your software, ATO online services, or send it to your BAS agent.
5. Pay from your tax account using the payment reference number on the BAS.

Software like Xero or MYOB does most of the calculation and can lodge directly to the ATO. Our Xero vs MYOB comparison covers which suits a sole trader tradie.

See Xero plans → Affiliate link. Opens the merchant site in a new tab.

Common GST mistakes tradies make

• Charging GST before you’re registered. You can’t charge GST or issue tax invoices until you’re registered.
• Forgetting to register when turnover hits $75,000. A busy year can push you over without you noticing. Check your rolling 12 month total regularly.
• Claiming GST on purchases without GST. Not everything you buy includes GST, and you need a tax invoice to claim credits on purchases over $82.50.
• Spending the GST. It’s the customer’s money you’re holding for the ATO. A separate account stops it disappearing into fuel and materials.
• Mixing personal and business spending. It makes reconciling slow and claims hard to support.

Compare: see MYOB plans → Affiliate link. Opens the merchant site in a new tab.

Records to keep

The ATO generally requires business records to be kept for five years. For GST, that includes tax invoices for sales and purchases, bank statements, and the working behind each BAS. Most accounting software stores invoices and receipt images for you, but make sure you can still get them out if you change software.

When to get help

A registered BAS agent can prepare and lodge your BAS, and a registered tax agent can do that plus your tax return and tax advice. Both are registered with the Tax Practitioners Board, and you can check their registration on its public register. For many tradies, paying someone for the first few quarters while you learn the routine costs less than fixing mistakes later.