AU · business-workflows
GST inclusive vs exclusive: compare Australian supplier quotes
Ex GST means before GST; GST inclusive means GST is already included. For an assumed 10% taxable supply, AUD 200 ex GST becomes AUD 220, so an equivalent AUD 215 inclusive quote is lower by AUD 5.
What ex GST and GST inclusive mean
Ex GST excludes the GST component. GST inclusive already contains it. These labels describe the price basis, not whether your business can claim the GST back. Before normalising two offers, establish whether they cover the same ordinary taxable supply.
The ATO’s Calculating GST on purchases explains the included-tax calculation and why dividing an inclusive total by 10 is the wrong way to find its GST component. This article applies that distinction to supplier quotes rather than attempting a BAS calculation.
Put both supplier offers on an inclusive basis
Imagine two quotes for the same service: AUD 200 ex GST and AUD 215 including GST. Assume the service has already been confirmed as an ordinary taxable supply at 10%. Adding AUD 20 GST to the first quote produces AUD 220. The inclusive AUD 215 quote is lower by AUD 5 before considering differences in service or other charges.
The second offer contains AUD 19.55 GST under the calculator’s single-supply cent convention, leaving AUD 195.45 before GST. That is a synthetic reverse calculation. It is not a supplier invoice or proof of a claimable credit.
Compare your two quotes
One ordinary taxable Australian supply at 10%. Synthetic examples, not actual offers or a tax-eligibility decision.
One already-classified amount per quote, assumed 10%; no currency conversion. Maximum 1,000,000,000,000 per input, two decimal places. Inputs stay on this device.
Quote B is lower by AUD 5.00 on the stated tax basis.
Quote A including GSTAUD 220.00
Quote B including GSTAUD 215.00
Country-engine results. Other charges and tax recovery are not calculated.
| Quote | Before GST | GST | Including GST |
|---|---|---|---|
| A · exclusive input | AUD 200.00 | AUD 20.00 | AUD 220.00 |
| B · inclusive input | AUD 195.45 | AUD 19.55 | AUD 215.00 |
Quote B would match Quote A at an inclusive price of AUD 220.00, with all other terms equal. A lower price is not a recommendation to choose a supplier.
For this pair, Quote B’s break-even inclusive price is AUD 220. At AUD 215 it is below that threshold. The AUD 5 gap compares cash totals on the stated basis, not the amount of a GST credit.
Use the full starting price in the correct mode
Select Add GST for an exclusive input and Remove GST for an inclusive input in the Australian GST calculator. Do not put AUD 215 into Add GST if the supplier has already included the tax. That would produce a new, higher amount and double-count GST for this comparison.
At the assumed ordinary treatment:
GST on an exclusive price = round(exclusive × 10 ÷ 100)
GST inside an inclusive price = round(inclusive ÷ 11)The GST Act’s ordinary value and GST provisions underpin the reference method. The cited compilation is dated 1 January 2026; application provisions and later changes require their own checks. This arithmetic does not classify a transaction.
A second example: different wording, no price difference
The ATO education page gives an inclusive purchase of AUD 352 with AUD 32 GST. Its derived exclusive value is AUD 320. Recasting those amounts as AUD 320 ex GST versus AUD 352 GST inclusive produces equal totals, not a cheaper first offer.
Different labels, equal totals
AUD 352 inclusive and AUD 32 GST reproduce the ATO education example; AUD 320 exclusive and the quote comparison are derived. Source amounts and derived comparison are distinguished below.
Both quotes have the same inclusive total.
Quote A including GSTAUD 352.00
Quote B including GSTAUD 352.00
Country-engine results. Other charges and tax recovery are not calculated.
| Quote | Before GST | GST | Including GST |
|---|---|---|---|
| A · exclusive input | AUD 320.00 | AUD 32.00 | AUD 352.00 |
| B · inclusive input | AUD 320.00 | AUD 32.00 | AUD 352.00 |
Quote B would match Quote A at an inclusive price of AUD 352.00, with all other terms equal. A lower price is not a recommendation to choose a supplier.
The published inclusive amount and GST are the independent source check. The derived exclusive amount and two-quote framing are our illustration. A source example supports the arithmetic; it does not endorse an actual purchase or establish your entitlement to a credit.
Keep the price comparison separate from credit decisions
An inclusive total is the relevant cash figure for comparing these assumed offers. An ex-GST comparison may also be useful for business planning, but it should not be presented as your final cost after credits. Eligibility is not implemented in this calculator.
The GST-free, input-taxed and ordinary taxable categories are not interchangeable. Do not force an uncertain supply into the ordinary treatment just to obtain a numerical answer. Input-taxed and outside-scope choices deliberately avoid a calculation. The Australian calculation guide explains the supported scope.
Check what each quote covers
Use this short sequence before comparing an Australian business purchase:
- Match the specification, quantity and service inclusions.
- Record whether each quoted amount is ex GST or inclusive.
- Confirm delivery and other charges are included on the same basis.
- Normalise the totals, then assess any credit question separately.
Do not infer GST status from AUD currency, an ABN or a familiar percentage alone. If the supplier’s wording is unclear, request a corrected breakdown. Keep mixed supplies and unsupported treatments out of this ordinary single-supply example.
The displayed figures cover one ordinary taxable supply not split into items. They are not a mixed-invoice calculation, cash-payment rounding rule, BAS or invoice-compliance check. The engine rounds GST first to the nearest cent, with half-cents up, within that narrow scope. Professional tax review remains pending.
Frequently asked questions
What does ex GST mean in a quote?
It means the displayed amount excludes GST. For an ordinary supply already confirmed as taxable at 10%, GST must be added to compare it with an inclusive offer.
Is GST 10% of the inclusive total?
No. At an assumed 10% treatment, GST is one-eleventh of the inclusive total before rounding.
Does the calculator calculate GST credits?
No. It separates the price components of one supported supply and does not decide credit entitlement or prepare a BAS.
Can two differently labelled quotes have the same price?
Yes. At an assumed 10%, AUD 320 ex GST and AUD 352 including GST both have an inclusive total of AUD 352 and GST of AUD 32.
Should I add GST to a GST-inclusive quote?
No. That would count the assumed GST twice for this comparison. Use the already-inclusive amount as the comparison total.
Use the same country engine
Add tax or extract the included amount with the calculation method used in these examples. Select the treatment applicable to your transaction separately.
Australia GST calculator