Tradie BAS Explained: What It Is, What's In It, and How to Lodge It

If you're registered for GST as a tradie, you've got a recurring obligation that trips up more business owners than almost anything else in the tax calendar: the Business Activity Statement, or BAS. Miss it and you face penalties. Get it wrong and the ATO will come back to you. Understand it properly and it becomes a straightforward quarterly task.

This guide explains what a BAS actually is, what goes in it, how to calculate it, and how to lodge it — written for tradies, not accountants.

What Is a BAS?

A Business Activity Statement is a form you lodge with the ATO to report and pay several taxes at once. For most tradies, the BAS covers:

• GST — the goods and services tax you've collected from clients, minus the GST you've paid on business purchases
• PAYG withholding — if you have employees, the tax you've withheld from their wages
• PAYG instalments — prepayments of your own income tax (once the ATO sets these up after your first tax return)

The BAS is how the ATO reconciles the GST flowing through your business. You collect 10% GST on every invoice you issue. You pay GST on most business expenses. The BAS is where you report the difference and either pay what you owe or claim a refund.

Who Has to Lodge a BAS?

You must lodge a BAS if you're registered for GST. GST registration is compulsory once your annual turnover exceeds $75,000. Below that threshold, registration is optional — but many tradies register anyway to claim back the GST they pay on tools, materials, and vehicles.

If you're not registered for GST, you don't lodge a BAS. You may still have PAYG withholding obligations if you employ staff, but that's handled differently.

How Often Do You Lodge?

Quarterly is the most common lodgement frequency for tradies, due 28 days after the end of each quarter:

If you use a registered BAS agent or tax agent, you typically get an extended deadline — often another month. This is one reason many tradies use an accountant or bookkeeper even just for BAS lodgement.

If your annual GST turnover exceeds $20 million, you lodge monthly. Almost no tradie business hits this threshold.

What Goes Into a BAS?

G1 — Total Sales

This is your total revenue for the quarter, including GST. If you invoiced $55,000 worth of work (with GST), you enter $55,000 at G1.

1A — GST on Sales

The GST component of your sales. For most tradies, this is G1 ÷ 11. On $55,000 of GST-inclusive revenue, the GST is $5,000.

1B — GST on Purchases (Credits)

This is the GST you've paid on business expenses — materials, tools, fuel, equipment, subcontractors. This is your input tax credit. On $22,000 of GST-inclusive purchases, the credit is $2,000.

Net GST Payable or Refundable

1A minus 1B = what you pay or what you get back.

In the example above: $5,000 – $2,000 = $3,000 payable to the ATO.

If you've spent more on business purchases than you've received in income (common when starting out or buying major equipment), you'll get a GST refund.

W1 — Total Wages Paid (If You Have Employees)

The gross wages and salaries you've paid this quarter.

W2 — PAYG Withholding

The tax you withheld from employee wages. This is a liability — it's not your money, it belongs to the ATO on behalf of your employees.

T1 — PAYG Instalment Income (If Applicable)

Once the ATO sets you up on PAYG instalments (usually after your first year of business), you prepay your own income tax quarterly. The amount is calculated by the ATO based on your previous year's income.

The Difference Between Cash and Accrual Accounting

When you register for GST, you choose how to report: cash basis or accrual basis.

Cash basis: You report GST in the period you actually receive or pay the money. If you invoice in June but get paid in July, the GST goes on your July–September BAS.

Accrual basis: You report GST in the period the invoice is issued, regardless of when it's paid.

Most sole trader tradies use cash basis — it matches your real cash position more closely and is simpler to manage. You must have turnover under $10 million to use cash basis.

The method you choose affects timing, not the total amount of GST you pay. But it can significantly affect which quarter you're paying it in.

How to Prepare Your BAS: Step by Step

Step 1: Make Sure Your Books Are Up to Date

Every invoice you've issued and every expense receipt you've captured needs to be recorded in your accounting software before you start. If you're using Xero, MYOB, or QuickBooks with bank feeds connected, this is mostly automated — transactions appear daily and just need to be categorised.

If you've got receipts stuffed in your glovebox, now's the time to photograph and enter them. A receipt app like Dext or Hubdoc makes this much faster.

Step 2: Reconcile Your Bank Account

Make sure every transaction in your accounting software matches your bank statement. Any unmatched transactions need to be coded before you can trust your BAS figures.

In Xero, this is done through the reconciliation screen — green ticks for every matched transaction. Aim to do this weekly rather than quarterly so BAS preparation takes 20 minutes instead of a day.

Step 3: Run Your BAS Report

Most accounting software generates a BAS summary report that pulls the figures directly from your coded transactions. In Xero: Reports > Tax > Activity Statement. This shows your G1, 1A, 1B, W1, W2 figures ready to transfer to your BAS.

Step 4: Review the Figures

Before lodging, sense-check the numbers:

• Does G1 match roughly what you've invoiced this quarter?
• Does 1B represent the GST on real business purchases only? (No personal purchases should be in here)
• Is your net GST roughly 10% of your profit? If it's wildly different, something may be miscoded.

Step 5: Lodge and Pay

Online through the ATO Business Portal or MyGov: Log in, navigate to your BAS, enter the figures, and submit. Payment is made by BPAY or EFT using the reference number on the BAS.

Through your accounting software: Xero, MYOB, and QuickBooks all allow direct BAS lodgement through an ATO-integrated connection. You review the figures in the software and submit from there.

Through a BAS agent or accountant: They lodge on your behalf. You review and approve, they handle submission. Most charge $150–$400 per quarter for BAS lodgement.

Common BAS Mistakes Tradies Make

Mixing personal and business expenses. Every personal purchase that gets coded as a business expense incorrectly inflates your 1B credit claim. The ATO audits input tax credit claims — inaccurate claims can result in penalties and interest.

Forgetting cash jobs. All income is reportable regardless of how it was paid. Cash jobs that don't go through the books are both a BAS issue (GST not reported) and an income tax issue (income not declared). The ATO uses data matching extensively.

Coding employee wages as contractor payments. Subcontractor payments and employee wages are treated differently on the BAS. Employees generate PAYG withholding obligations. Subcontractors who provide their own ABN and invoice you do not.

Not setting money aside for GST. The most common BAS disaster for new tradies is spending the GST they've collected on operations, then facing a bill they can't pay. The GST on your invoices is never your money — set it aside in a separate account or at least mentally quarantine it.

Missing the deadline. Late lodgement results in a Failure to Lodge (FTL) penalty — one penalty unit (currently $330) per 28-day period, up to five periods. Late payment incurs General Interest Charge (GIC) on the amount owed. Both are avoidable with a calendar reminder.

Setting Up to Make BAS Easy

The tradies who dread BAS time are almost always the ones whose books are a mess when the due date arrives. The ones who find it simple are the ones who've set up proper systems.

The basics that make BAS painless:

Accounting software with bank feeds: Xero, MYOB, or QuickBooks connected to your business bank account. Transactions arrive automatically; you categorise them, usually in a few clicks per transaction.

Receipt capture as you go: Photograph every receipt immediately — before it fades, gets washed, or goes missing. A dedicated app like Dext or Hubdoc (free with Xero Growing) makes this effortless.

Weekly reconciliation: 10–15 minutes per week keeping your books current means BAS preparation takes 20 minutes at quarter end, not a full day.

A separate GST account: Move 10% of every payment received into a separate account earmarked for GST. When the BAS bill arrives, the money is already there.

A BAS agent or accountant: For most tradies, professional lodgement is worth the cost — they catch errors, get you extended deadlines, and take the liability off your plate if something is questioned.

What Happens If You Can't Pay?

If your BAS is due and you can't pay the full amount, lodge anyway. The penalty for not lodging is separate from the penalty for late payment, and lodging on time avoids the FTL penalty even if you can't immediately pay what you owe.

Contact the ATO to set up a payment arrangement before the due date if possible. The ATO is generally willing to work out instalment plans for tradies who engage proactively rather than ignoring the debt.

The worst outcome is ignoring a BAS debt. It accumulates GIC at a rate that compounds daily, and the ATO has significant powers to recover tax debts including garnishing bank accounts and issuing director penalty notices.

BAS in a Nutshell

Your BAS is a quarterly report to the ATO on the GST flowing through your business, plus PAYG withholding if you have employees. It's due 28 days after each quarter ends. The net GST you owe is what you've collected from clients minus what you've paid on business expenses.

Set your books up properly, reconcile weekly, capture your receipts, and BAS time becomes a quick review rather than a quarterly crisis.

Tradie Money AU helps Australian tradies understand their tax and financial obligations. This article is general information only — speak with a registered BAS agent or tax agent for advice specific to your situation.