GST Excluded vs Included: What It Means in Australian Contracts

If you run a small business, you’ve probably seen pricing described as “GST excluded”, “GST inclusive”, “ex GST”, or “+ GST”. It can feel like a small detail - until it causes a payment dispute, a margin blow-out, or an unhappy customer who says they thought the quoted price was the final price.

The good news is that you can reduce a lot of GST-related confusion (and risk) with clear contract drafting. In this article, we’ll walk you through what GST-excluded pricing means in practice, when it’s appropriate, and the key clauses to include so your pricing and invoicing are consistent from quote to payment.

We’ll keep this focused on what matters most for small businesses: clarity, enforceability, and avoiding disputes. This article is general information only (not tax advice) - if you’re unsure whether GST applies to a particular supply, or how to treat GST on invoices and payments, it’s best to check with your accountant or a registered tax agent.

What Does “GST Excluded” Actually Mean In A Contract?

When your contract says a price is GST excluded, it generally means the price stated is before GST is added (if GST applies).

In practical terms:

• If your contract price is $10,000 GST excluded, and GST applies at 10%, the customer will usually pay $11,000 in total.
• If your contract price is $10,000 GST included, the customer pays $10,000 total (and you account for the GST component within that amount).

The important point is that describing a price as “GST excluded” isn’t just a pricing style - it’s a legal and commercial allocation of who bears the GST cost (and how it is calculated and charged), subject to the GST law applying to the supply.

Why “GST Excluded” Can Cause Disputes

Disputes tend to pop up when:

• a quote says “GST excluded”, but the contract doesn’t clearly repeat or define it
• the invoice adds GST, but the customer says the contract price was “fixed”
• the parties disagree about whether GST applies to that supply at all
• the contract price changes (variations, extras, change requests), but the GST treatment isn’t addressed

Even if you’re confident you “always charge + GST”, it’s still worth making sure your documentation backs you up - especially if you’re dealing with bigger projects, longer-term service arrangements, or repeat customers.

It can also help to be consistent in how you describe pricing across your documents (for example, using “ex GST” consistently rather than mixing “GST excluded”, “+ GST” and “GST not included”). If you want to align your language, “ex GST” is commonly used in Australia and typically means the same thing: ex GST.

GST Excluded vs GST Included: Which One Should You Use?

There’s no single “right” approach for all businesses. The best option depends on your customers, your industry norms, and how your pricing is presented (particularly online).

When “GST Excluded” Often Makes Sense

Many businesses use GST excluded pricing when:

• you mainly sell to other businesses (B2B) that can claim GST credits
• you quote large project amounts, and GST is treated as a separate line item
• your pricing model relies on a clear “base price” plus tax
• you regularly update prices and want to avoid recalculating “inclusive totals” every time

For example, service providers (consultants, agencies, trades, professional services) often quote “$X + GST”. In those cases, GST excluded pricing is common - but you still want the contract to spell out that GST (if applicable) will be added and paid by the customer.

When “GST Included” Is Often Safer (Or Required)

GST included pricing can be the better option when:

• you sell to consumers (B2C) who expect a final, all-up price
• you advertise prices publicly (website, social media, signage)
• you want to minimise back-and-forth about totals
• you’re concerned about Australian Consumer Law (ACL) pricing expectations

Australian pricing rules can be strict about how prices must be displayed in certain contexts. If you’re advertising prices to the public, you need to be careful that your “GST excluded” messaging doesn’t create a misleading impression about the final price payable. This is why many businesses use GST inclusive pricing in consumer-facing marketing, even if they still use GST excluded pricing in B2B proposals.

If you’re unsure how to present this clearly, it’s worth understanding the difference between GST inclusive vs exclusive wording and what customers typically understand from each.

Common “GST Excluded” Traps In Quotes, Proposals And Invoices

In practice, it’s not enough to write “GST excluded” once and hope for the best. Your quote, contract, invoice, and payment terms should all tell the same story.

Trap 1: Your Quote Says GST Excluded, But Your Contract Doesn’t

This is one of the most common issues. You might send a quote with “$5,000 + GST”, then later sign a contract that just states “Price: $5,000” with no GST wording.

If the relationship breaks down, the customer may argue that the signed contract reflects the final agreed price, and that your quote is just an earlier document. You don’t want to be stuck debating which document controls the deal.

If you use quotes regularly, it helps to understand when the quote can become binding in the first place. Depending on the wording and acceptance process, a quotation can be legally binding, which is another reason your quote and contract should align.

Trap 2: “GST Excluded” But The Customer Thinks It’s A Fixed Price

Sometimes customers understand “GST excluded”, but still assume your price is “fixed” and won’t change. If you later add GST (or there are variations), they may feel blindsided - even if you’re legally correct.

The solution is not just legal wording - it’s also presentation. Make the pricing structure obvious:

• Base price (GST excluded)
• GST amount (or that GST will be calculated at the applicable rate)
• Total payable (if you can calculate it upfront)

Even in B2B deals, giving a clear “total including GST” figure can reduce friction.

Trap 3: Deposits And Progress Payments Aren’t Clear About GST

If your contract has a deposit or milestone payments, you should clarify whether each amount is GST excluded or included (and how GST will be handled for each invoice).

This is particularly important if you’re trying to manage cash flow carefully. A well-drafted payment clause can avoid disputes about what is due and when - especially where tax invoices are required before payment. Your invoice payment terms should match your contract’s GST position.

Trap 4: Online Checkout Or Advertised Prices Don’t Match Your Contract Pricing

If you sell online, you might advertise GST inclusive pricing (common for consumer sales), but your wholesale or corporate contract templates might default to GST excluded pricing.

That’s not automatically wrong - but you should ensure:

• your customer knows which pricing model applies before they commit
• your contract and your website terms don’t contradict each other
• your invoices reflect the correct price basis

If you’re actively switching between consumer and business pricing models, it can help to standardise the language you use around displaying and charging prices so you don’t accidentally create inconsistent customer expectations.

How To Draft A Clear GST Excluded Clause (What To Include)

If you want to use GST excluded pricing in a contract, the goal is to remove ambiguity. A strong clause usually covers the points below (in plain English, not legal jargon for its own sake).

1. State That The Price Is GST Excluded

This sounds obvious, but it needs to be explicit. Your contract should clearly say something like “all prices are GST excluded unless stated otherwise” or “the fees are exclusive of GST”.

Be careful about mixing terms. If you use “GST excluded” in one place and “inclusive” in another, make sure it’s clearly intentional (for example, a fixed fee that is GST included, but variations that are GST excluded).

2. Explain Who Pays GST (And When)

A common approach is to say the customer must pay GST in addition to the price, typically at the time they pay the invoice. Depending on the arrangement, your clause might link GST payment to when you issue a tax invoice or when payment is due under your payment terms (and you should ensure your invoicing process matches the contract wording).

3. Deal With Changes In GST Or Tax Law

GST rates don’t change often, but contracts can run for years. It’s worth addressing what happens if tax law changes. For example:

• if GST increases or a new tax applies
• if an exemption is removed
• if the supply is later determined to be taxable when the parties thought it wasn’t (or vice versa)

The goal is to avoid a situation where you have to renegotiate pricing mid-contract.

4. Cover Variations, Extras And Out-Of-Scope Work

Disputes often arise when the base contract price is GST excluded, but additional work is discussed informally and invoiced later. Your contract should be consistent that:

• variations are also GST excluded (unless otherwise agreed), and
• GST will be added to variation invoices.

If your business delivers services with a changing scope (like marketing, software development, consulting, or trades), it’s a good idea to set out how variations are approved (in writing, via email, through a signed change order, etc.).

5. Make Sure The GST Clause Matches Your Other Terms

Your GST wording shouldn’t sit in isolation. It needs to align with:

• your payment terms (including invoice timing and due dates)
• your refund or cancellation approach (especially in consumer-facing services)
• any late fees or interest clauses
• your definitions section (if you have one)

As a general rule, if a customer can read your contract and still ask “so what do I actually pay?”, the drafting needs tightening.

How GST Wording Interacts With Australian Consumer Law (And Why It Matters)

Even if your contract is mainly B2B, it’s worth remembering that the Australian Consumer Law (ACL) can apply to certain business-to-business transactions as well (for example, depending on the goods or services and the contract value). The key takeaway is that pricing should be presented clearly and consistently so customers understand the total amount payable.

The bigger issue for many small businesses is this: pricing that is unclear or inconsistent can create risk under the ACL, particularly where a customer could argue they were misled about the true total price.

Here are a few practical steps that help:

• Keep your advertised price and contract price consistent (or clearly explain why they differ).
• Avoid “hidden” GST in consumer-facing transactions - if you’re advertising to the public, it’s usually safer to show GST-inclusive totals.
• Use simple labels like “including GST” or “+ GST” and repeat them where it matters (quote, order form, invoice).

If you’re also reviewing your broader customer-facing terms, it can help to sanity-check whether the agreement is enforceable and consistent. A contract doesn’t need to be complicated to be valid, but it does need the right legal foundations in place, including clear offer, acceptance and pricing terms. This is part of what makes a contract legally binding.

Key Takeaways

• In most contracts, GST excluded means the stated price is a base amount and GST (usually 10% if it applies) will be added on top.
• GST excluded pricing can work well in B2B arrangements, but you should make it crystal clear in your contract, quote, and invoices to avoid disputes.
• Common problems happen when the quote and contract don’t match, deposits and milestones aren’t clear about GST, or variations are charged inconsistently.
• A strong GST clause should confirm the price is GST excluded, who pays GST, when GST is payable under your invoicing/payment process, and how variations and changes in tax law are handled.
• If you advertise prices publicly (especially to consumers), consider whether GST-inclusive pricing is safer to avoid confusion and reduce ACL risk.

If you’d like help drafting or reviewing a contract so your pricing and GST wording is clear from the start, you can reach us at 1800 730 617 or team@sprintlaw.com.au for a free, no-obligations chat.