GST on Optical Dispensing: The BAS Mistake Most Melbourne Optometrists Are Making

The GST Split in Optometry — and Why It's Routinely Ignored

The health services GST exemption under the A New Tax System (Goods and Services Tax) Act 1999 covers professional health services provided by registered health practitioners — including optometrists. An eye examination is a GST-free supply. But the exemption applies to the service, not to goods supplied in connection with that service. Spectacle frames, prescription lenses, contact lenses, contact lens solutions and sunglasses are all taxable supplies at 10% GST.

Most Melbourne optometry practices apply one treatment or the other to everything. The practice that codes all income as GST-free because "we're a health provider" is understating its GST liability on all dispensing revenue — which, in a full-service practice, typically represents 60–70% of total income. The practice that applies GST to everything, including eye examinations, is overcharging patients and overpaying the ATO on clinical services. Both errors compound quarterly and accumulate into a material liability over time.

What the Law Actually Says

Section 38-7 of the GST Act exempts supplies that are "professional services" by a "recognised health professional" in their professional capacity. The ATO's guidance confirms that the exemption applies to the optometric consultation — the clinical examination and professional judgement about the patient's visual health — but not to the optical goods that may be prescribed as a result of that consultation.

The supply of spectacle frames is the supply of goods — taxable. The supply of prescription lenses is the supply of goods — taxable. The supply of contact lenses is the supply of goods — taxable. This is not a grey area or a matter of professional judgement. It is settled ATO guidance that has been consistent since the GST was introduced in 2000.

The Mixed Supply Problem

The complication arises when a patient has a consultation and is dispensed glasses in the same visit — which is the majority of optometry appointments. This is a mixed supply: the professional service (GST-free) and the goods (taxable) delivered in a single transaction.

For GST purposes, a mixed supply must be apportioned. The invoice needs to separately identify the professional service fee and the optical goods components, with GST applying only to the goods. A practice that issues a single invoice for "$350 — eye examination and spectacles" with no itemisation cannot correctly apportion the GST treatment — it must either apply GST to the whole amount (overcharging on the clinical component) or apply GST-free treatment to the whole amount (undercharging on the goods component). Neither is correct.

The solution is invoice templates that always itemise separately: a consultation line at the professional service fee (GST-free) and a dispensing line for frames and lenses (including GST). This is a Xero setup question as much as a bookkeeping one — and practices that set it up correctly from the start avoid the problem entirely.

The Scale of the Error in a Typical Melbourne Practice

Consider a Melbourne optometry practice with annual revenue of $800,000 — a realistic figure for a busy suburban practice. If dispensing represents 65% of that revenue ($520,000), and if GST has not been applied to dispensing income, the practice has understated its GST liability by $52,000 per year ($520,000 ÷ 11 × 1). Over three years — the standard ATO review period — that's a $156,000 liability before interest.

The general interest charge (GIC) applies from the date each quarterly BAS was due. At the current GIC rate, three years of compounding interest adds materially to the base liability. If the ATO determines the error involved recklessness, a penalty of up to 50% of the tax shortfall applies on top. This is not a theoretical scenario — optometry GST classification is a known area of ATO review focus for allied health practices.

How to Fix It — Past BAS Returns and Future Coding

For a practice that has been applying incorrect GST treatment, the path forward involves two things: correcting past BAS returns and fixing the Xero setup for future periods.

Past BAS corrections can be made by lodging amendments through the ATO's business portal. Proactive voluntary amendment before any ATO contact generally results in the penalty being remitted entirely — only the interest charge applies. Waiting until the ATO raises the issue removes this advantage. A registered BAS agent (like True Tally) can lodge the amendments and handle the ATO correspondence.

For future periods, the fix is a correctly structured Xero chart of accounts with separate income accounts for clinical and dispensing revenue, the right GST tax codes applied to each, and invoice templates that itemise the professional service and goods components. Once this is set up, the BAS populates correctly automatically — no manual adjustment required each quarter.