GST & BAS Calculator

The rate, and how to take GST out of a figure

GST is 10%, charged on the GST-exclusive price. A $100 service becomes $110, and the $10 of GST is 10% of the $100, not 10% of the $110. That direction is what catches people out, because bank deposits and supplier invoices are almost always the inclusive figure.

To take GST out of a GST-inclusive amount, divide by 11. A $110 invoice contains $10 of GST. Subtracting 10% instead gives $11, which overstates the GST by a dollar and understates the income.

This matters most where you are reconciling a bank deposit to a BAS, because the deposits are GST-inclusive and the labels on a BAS are not. If a figure is a cent out across a year of transactions, this is usually why.

GST-free does not mean you lose your credits

This is the single most expensive misunderstanding in practice GST. A supply being GST-free means you do not charge GST on the way out; it does not mean you forfeit the GST you paid on the way in. You still claim input tax credits on purchases used to make GST-free supplies.

That distinction is the entire difference between GST-free and input-taxed. Input-taxed supplies, such as most financial supplies, genuinely do deny credits. GST-free supplies do not.

The practical consequence surprises a lot of practice owners: a practice whose income is mostly GST-free will usually receive a refund from the ATO rather than a bill. If your BAS always shows an amount payable despite almost entirely Medicare-funded income, that is worth investigating.

What is GST-free and what is not

Clinically necessary treatment provided by a registered health practitioner is generally GST-free under section 38-7 of the GST Act. Prescriptions dispensed on a valid prescription are also GST-free.

Cosmetic procedures are taxable. This is where practices most often get caught, because the line between a reconstructive procedure and a cosmetic one is not always obvious, and it turns on the purpose of the treatment rather than the procedure itself. A procedure performed to correct or reconstruct following illness, injury or congenital abnormality is treated differently from the same procedure performed purely for appearance.

Retail sales (skincare, supplements, devices) are taxable. Non-clinical services such as medico-legal reports, some corporate health work and room rental may also be taxable depending on the arrangement.

Dental practices: clinical treatment versus cosmetic work

Section 38-10 covers dental as a listed health service, which is why a routine check-up, a filling, a root canal or an extraction comes off the bill GST-free by default. What trips practices up is that the exact same procedure can go either way depending on why it was done: a crown to restore a broken tooth is GST-free, the same crown chosen purely to reshape an otherwise healthy one is not, and neither is whitening or veneers picked for appearance rather than to fix decay, trauma damage or a medical condition.

Two patients, identical work, different GST treatment, because the classification follows the purpose, not the procedure.

Retail items sold at the front desk without any clinical fitting, a take-home whitening kit, a mouthguard handed over the counter, are ordinary taxable sales whoever rings them up.

Physiotherapy: why massage on its own is not GST-free

The one thing every physio should know before invoicing a massage: it does not automatically qualify as GST-free just because a registered physiotherapist performed it. Physiotherapy is a listed service under s38-10, so assessment and treatment are GST-free, but the ATO treats remedial and relaxation massage as its own thing, not itself a listed service, so a stand-alone massage booking is taxable unless it is genuinely part of a clinical treatment plan that followed an assessment.

The same logic applies to bundled offerings. Pair a clinical assessment with ongoing gym-based coaching and you have created two supplies, not one, so the invoice needs to split the GST-free assessment from the taxable coaching rather than pricing the whole package as if it were exempt.

DVA and insurer-funded treatment gets assessed on the same clinical test as anyone else, but DVA billing runs through its own recipient-created tax invoice arrangement, which is a paperwork requirement layered on top of the underlying classification, not a substitute for it.

Psychology: the report and third-party trap

Where psychology practices actually get caught is not the therapy itself. Clinical consultations and treatment of a patient are GST-free as a listed service. It is report and assessment work where two separate tests can quietly defeat GST-free status. One is who is actually paying: a third party only counts as an eligible GST-free payer if it is an insurer, a statutory compensation scheme, a CTP scheme or a government agency, so a solicitor, an employer or a court does not qualify, however the invoice is worded. The other is whether the work is treatment at all: a forensic assessment written for a legal process is not treatment of the person being assessed, full stop.

Put those together and a family law parenting capacity assessment commissioned by a solicitor fails on both counts, essentially always taxable. A workers compensation assessment sits closer to the line since the insurer can qualify as an eligible payer, but it still comes down to the specific engagement rather than a blanket rule.

Separately, executive coaching, corporate wellbeing work and supervising another practitioner’s registration hours are taxable too, no matter how clinical the underlying skill set, because none of it is treatment of a patient.

Podiatry: orthotics, and where the goods-versus-service line falls

Orthotics are where podiatry GST gets genuinely complicated, and it is worth getting right because the dollar values add up. A custom orthotic that has been assessed, cast and fitted as part of a consultation is generally GST-free, either because it is a good necessary to a GST-free service or because it qualifies on its own as a medical aid for a diagnosed condition that is not in general use. Pull the same-looking insole off a display shelf with no assessment behind it and it is an ordinary taxable retail sale, regardless of what it is sold next to.

The rest of podiatry follows the usual s38-10 pattern: clinical assessment and treatment of a diagnosed condition, diabetic foot checks, nail and skin pathology treated clinically, is GST-free by default, while cosmetic nail and pedicure work with no clinical basis is taxable on the same purpose test that applies across dental and medical work.

Invoicing should reflect the distinction rather than blur it: an orthotic tied to a diagnosed condition and made through a clinical consultation is a different supply, for GST purposes, from the identical-looking product sold off the shelf.

Optometry: the eye test is GST-free, the frame usually is not

A routine eye examination by a registered optometrist is GST-free, generally under section 38-7 where a Medicare benefit is payable for the consultation, or under section 38-10 as a listed health service where it is not. Dispensing what the examination prescribes is a separate question, and it is where optometry practices most often get the classification wrong.

Prescription lenses are GST-free as a medical aid and appliance, but the frame is not. The Federal Court's decision in the Luxottica case confirmed that a pair of spectacles is a mixed supply rather than one exempt item: the lens component is GST-free and the frame component is taxable, apportioned on the price actually agreed between the practice and the patient. An invoice that treats a whole pair of glasses as exempt because a prescription was involved somewhere in the sale has usually got the frame wrong.

Non-prescription sunglasses, reading glasses sold over the counter with no examination behind them, and contact lens solution are ordinary taxable retail sales, on the same purpose-and-assessment test that separates a GST-free orthotic from a shelf insole in podiatry, or a reconstructive procedure from a cosmetic one in dental. What decides the GST treatment was never the object on the shelf; it is whether a clinical assessment prescribed it for a diagnosed vision impairment.

Apportionment is where the errors happen

You can only claim credits for the creditable portion of your purchases. Two things reduce that portion: private or non-creditable use, and use in making input-taxed supplies.

What does not reduce it, contrary to what many practices assume, is the GST-free share of your income. Apportioning credits by the ratio of taxable income to total income is a common error that leaves money unclaimed.

If you use a vehicle, a phone or a home office partly privately, reduce the private percentage here and the calculator will apply it.

The registration threshold catches practices out

The $75,000 registration threshold counts GST-free income. A practice billing $200,000 in Medicare-funded consultations has GST turnover of $200,000 even though it charges no GST at all, and is well over the threshold.

Registration is not optional at that point, and the obligation to register arises from turnover rather than from whether you are charging GST.

Below the threshold it is a choice, and for a practice whose income is almost entirely GST-free the choice is worth doing properly. GST-free supplies attract input tax credits, so a practice that registers voluntarily charges no GST on its clinical work while still claiming credits on what it buys. On those facts registration can produce a refund rather than a cost.

The catch is what it does to any taxable income. Registering means charging GST on the taxable part, so a practice with cosmetic work or retail sales becomes 10% more expensive to those patients than an unregistered competitor. It also brings BAS obligations, which cost something to administer. The answer is not the same for every practice, and it is worth a conversation rather than an assumption.

What this calculator does not do

It does not determine whether a specific procedure is GST-free. That is a judgement about the purpose of the treatment, and it is the part most likely to be disputed on review.

It also does not replace your BAS. It is a planning tool for understanding your position and sense-checking what your software produces.

Where a material amount turns on the classification of a procedure, get advice from your accountant or tax agent before lodging.