GST, BAS and taxation fundamentals

Why it matters

Tax debts are the most common reason small businesses end up in serious trouble with a creditor, and the ATO is a creditor with unusual powers. Yet the underlying cause is almost never the amount of tax; it is spending money that was collected on someone else’s behalf. Owners who understand what each obligation is, when it falls due and how to quarantine the cash find that tax becomes a boring administrative routine, which is exactly what it should be.

How GST actually works

Goods and services tax is a 10% tax on most goods and services sold in Australia. If you are registered, you add GST to your taxable sales and issue tax invoices showing it. You also pay GST on most of your business purchases, and you can claim that back as GST credits. What you owe the ATO is the difference: GST collected on sales minus GST paid on purchases. If credits exceed collections, for example in a quarter of heavy equipment buying, the ATO refunds the difference.

Registration is compulsory once your turnover reaches the registration threshold (check the current figure with the ATO) and optional below it. Some sales are GST-free (many basic foods, some health and education services, exports) and some are input-taxed (such as residential rent and most financial supplies). Your accounting software handles the coding, but you need to set the correct tax code on each sale and purchase, and you need a valid tax invoice to claim credits above a small amount.

What the BAS reports

The Business Activity Statement is the ATO form on which registered businesses report and pay several obligations at once. For most small businesses it is lodged quarterly, though monthly and annual cycles apply in some situations. The main sections are GST (sales, purchases and the net amount), PAYG withholding (tax withheld from employee wages), PAYG instalments (prepayments of your own income tax) and, for some businesses, fuel tax credits and other items.

Quarterly BAS lodgement and payment are generally due on the 28th of the month after the quarter ends, with extra time for the December quarter and for businesses lodging through a registered BAS or tax agent. Lodging late attracts penalties even if no money is owed, and interest accrues on unpaid amounts, so lodging on time and arranging a payment plan if needed is always better than going quiet.

• G1 total sales and 1A GST on sales, 1B GST on purchases.
• W1 total wages and W2 amount withheld, if you have employees.
• T7 or T1 PAYG instalment amount, if you are in the instalment system.
• Net amount payable or refundable at the bottom.

PAYG, income tax and super are separate flows

PAYG withholding is tax you take out of employee wages and send to the ATO. It is reported on the BAS but it was never your money. Single Touch Payroll reporting means the ATO already knows the figures from each pay run. PAYG instalments are different: they are prepayments of the business owner’s or company’s own income tax, calculated by the ATO from your last return, and credited against the tax bill when the annual return is lodged.

Income tax itself depends on structure. Sole traders and partners include business profit in their personal returns and pay at individual marginal rates. Companies pay company tax on profit, with a lower rate available to smaller base rate entities. Superannuation guarantee contributions for eligible workers are a separate obligation with their own rate and deadlines, and late super is treated harshly. Check the current rate and payment timing rules with the ATO, as both have been changing.

A system that makes tax boring

The habit that solves most tax stress is quarantining. When a customer pays, move the GST portion and a sensible percentage for income tax into a separate account the same day. When you run payroll, move the PAYG withheld and the super at the same time. The main account then shows money you can actually spend, and the BAS is paid from money that was always waiting for it.

Pair that with a registered BAS or tax agent who lodges for you, reviews coding each quarter and gets you the extended deadlines. SMBH Consulting works alongside owners’ accountants to put the bookkeeping rhythm and set-aside system in place so quarter-end is routine, but the lodgement and tax decisions always sit with your registered agent.

How to stay on top of GST and BAS

1. Register correctly ABN first, then GST once required or chosen, then PAYG withholding before your first employee is paid.
2. Set GST codes in your software Default codes on every product, service and supplier, so coding is right without thinking.
3. Open a tax set-aside account Transfer GST, income tax and payroll obligations as money arrives and as payroll runs.
4. Reconcile weekly Clean books are what make a BAS quick and accurate.
5. Run the BAS checklist at quarter end Reconcile, check codes, confirm invoices, finalise payroll.
6. Lodge and pay on time Through your software, Online services for business or your registered agent. Set calendar reminders two weeks ahead.
7. If you cannot pay, call early The ATO offers payment plans. Lodge anyway; silence is what triggers penalties and enforcement.

Real-world example

A Perth electrician works through a quarterly BAS

Swan Electrical is a sole trader business run by Dev, registered for GST and reporting quarterly on a cash basis. In the September quarter his customers paid him $66,000 including GST, so his GST collected is $6,000 (one eleventh). He paid $22,000 including GST for materials, fuel, software and insurance, giving GST credits of $2,000. His net GST is $4,000. He has no employees, so there is no PAYG withholding, but the ATO has placed him in the PAYG instalment system and his quarterly instalment is $3,800.

His BAS total is $7,800. Because he has been moving one eleventh of every customer payment plus 20% of the remainder into his set-aside account all quarter, there is $18,900 waiting. He pays the BAS on the 28th, leaves the rest in the account for his annual income tax, and spends the afternoon on a job rather than on the phone to the ATO.

Common mistakes

• Spending GST as if it were revenue The single most common cause of ATO debt. The GST in every payment belongs to the ATO; move it the day it arrives.
• Claiming credits without a tax invoice Credits above a small threshold need a valid tax invoice. Keep digital copies attached to the transaction.
• Not lodging because you cannot pay Late lodgement penalties apply regardless of payment. Lodge on time, then arrange a payment plan.
• Wrong GST codes on GST-free or private items Claiming GST on bank fees, insurance stamp duty, wages or personal purchases leads to amendments and interest.
• Paying super late Late super loses its tax deduction and attracts a charge. Pay it with every payroll run, not at the last minute.

KPIs to track

• Set-aside coverage Cash in the tax account divided by estimated GST, PAYG and income tax owing. Target 100% or more at all times.
• BAS lodged on time A simple yes or no each quarter. Four out of four is the only acceptable score.
• ATO account balance Check your integrated client account regularly. It should be zero or in credit between due dates.
• Super paid on time Every contribution received by the fund before the deadline. Track it as a hard compliance measure.

Frequently asked questions

Should I register for GST before I have to?

If your customers are mostly GST-registered businesses, voluntary registration lets you claim credits on your purchases and makes little difference to them. If you sell to consumers, adding 10% to your prices may hurt sales. Your accountant can model it for you.

Can I lodge the BAS myself?

Yes, through your accounting software or the ATO’s Online services for business. Many owners still use a registered BAS agent for the review and the extended lodgement dates.

What happens if I make a mistake on a BAS?

Small errors can usually be corrected on a later BAS; larger ones need a revision. Fixing an error yourself is treated far more leniently than having the ATO find it.

What is the difference between a BAS agent and a tax agent?

Both are registered with the Tax Practitioners Board. A BAS agent can prepare and lodge BAS and advise on GST and payroll matters. A tax agent can also prepare income tax returns and give broader tax advice.

Key takeaways

• GST, PAYG withholding and super are collected on behalf of others; quarantine them on receipt.
• The BAS reports GST, PAYG withholding and PAYG instalments together, usually quarterly.
• Lodge on time even when you cannot pay; penalties follow silence, not honesty.
• Clean, coded, reconciled books make quarter-end an hour’s work.
• Rates, thresholds and deadlines change: confirm them with the ATO or your registered agent.