How the R&D tax offset is calculated, and how to think about your potential benefit

This article provides general information only and is not tax, financial, or legal advice. You should confirm your position with a registered tax agent because rules and rates change.

For many Australian businesses doing genuine research and development, the R&D Tax Incentive can represent a significant cash-flow lever. But the mechanics of how the benefit is calculated are frequently misunderstood. Founders, CFOs, and their advisors hear terms such as 'notional deduction', 'refundable offset', and 'aggregate turnover threshold' and end up with a fuzzy picture of what the dollars might look like.

Getting the calculation right matters. The numbers drive budgeting decisions, influence project scoping, and determine the strength of a claim under ATO scrutiny. In this step-by-step guide we explain how the R&D tax offset is calculated, and how to think about your potential benefit, in plain terms. We stick to the core mechanics, name the official sources, and flag the points where you will need your registered tax agent.

Whether you are new to the incentive or already have an AusIndustry registration, understanding this calculation helps you estimate value and plan the claim process. It also shows why quality evidence and a proper accountant review make all the difference.

Prerequisites

Before you start to calculate an R&D tax offset amount, a few conditions must be in place. Tick these off first.

• Your company must be an R&D entity: an Australian resident company that incurred notional R&D expenditure during the income year. (Specific corporate structures and foreign entities may also qualify under certain tests; your accountant can advise.)
• The company must have registered one or more R&D activities with AusIndustry within 10 months of the end of the income year. Without a valid registration, no offset can be claimed. GrantsMAX can help you identify and document eligible activities before that deadline.
• You need to understand the eligible R&D expenditure categories, because the offset is calculated on the notional deduction, which is the total of specific costs incurred on registered R&D activities.
• You need a registered tax agent (or an accountant who is a registered tax agent) who will review, refine, and lodge the claim. This is not optional. The agent relies on accurate, contemporaneous records, so your internal books must be up to date.
• Your company must have aggregated turnover information to determine which offset rate applies: refundable or non-refundable.

If any of these boxes are not ticked, step back and address them first. Business owners and CFOs can use GrantsMAX to discover what they may be eligible for and get a clear picture of their position before engaging an accountant.

Now, let's walk through the calculation step by step.

Step 1: Confirm your R&D eligibility and register your activities

The R&D Tax Incentive is administered jointly by AusIndustry and the ATO. AusIndustry, part of the Department of Industry, Science and Resources, assesses the technical eligibility of the R&D activities, while the ATO assesses the expenditure.

Eligible R&D activities fall into two categories: 'core' R&D activities and 'supporting' R&D activities. Core activities are experimental activities whose outcome cannot be known or determined in advance and that satisfy the 'hypothesis-driven experimental process' test. Supporting activities are directly related to core activities. For a plain‑English breakdown, see our guide: What is the R&D Tax Incentive?

Before you can claim the offset, you must register each activity with AusIndustry. The registration must describe the activities clearly and link them to the eligibility criteria. GrantsMAX drafts activity narratives from your data, which helps you and your accountant review and refine them ahead of registration.

Pro tip: Registration is not the same as lodging a tax return. You register with AusIndustry, then later your accountant includes the R&D schedule in the company tax return. Both steps are essential.

Step 2: Identify and calculate your notional deductions

The R&D tax offset is calculated on what the legislation calls 'notional deductions'. A notional deduction is the total amount of R&D expenditure that would be deductible under general tax law if there were not a specific R&D provision. In practice, you add up the eligible costs incurred during the income year on registered R&D activities.

According to the ATO, eligible R&D expenditure can include:

• employee salary and wage costs for time spent on R&D activities
• contractor expenditure engaged for R&D work
• consumables and materials used in experiments
• depreciation on plant and equipment used for R&D
• overheads such as rent, power, and administrative support that relate to R&D activities
• other costs directly incurred on R&D

Some expenditure is explicitly excluded (interest, expenditure on land and buildings, and costs that are not at risk, for example). The ATO’s step-by-step guide explains the types of expenditure that can form part of the notional deduction.

To calculate the notional deduction, you need to:

1. Identify all costs that relate to registered R&D activities.
2. Apply apportionment where a cost partly relates to R&D and partly to non‑R&D activities. Reasonable methods include time‑tracking, floor‑area calculations, or direct usage logs.
3. Exclude any expenditure that is not eligible under the R&D rules.
4. Total the remaining eligible expenditure for the income year.

This total is your notional deduction amount. It is the base on which the offset rate is applied.

Warning: Inflating costs or including non‑eligible items is one of the most common triggers for ATO reviews. Keep contemporaneous records that link each dollar to a specific registered activity. GrantsMAX builds an evidence index across your emails, invoices, and timesheets to support the cost structure.

Step 3: Determine which offset rate applies, refundable or non‑refundable

The R&D tax offset rate depends on your company’s aggregated turnover for the income year. The key threshold is currently $20 million.

• If your company’s aggregated turnover is less than $20 million, you may be entitled to the refundable R&D tax offset. The ATO states that the refundable offset rate is 43.5% of the notional deduction (for income years starting on or after 1 July 2021). Because this offset is refundable, the ATO will refund any excess after the offset reduces your tax liability to zero.
• If your aggregated turnover is $20 million or more, you may be entitled to the non‑refundable R&D tax offset. The non‑refundable rate is 38.5% of the notional deduction (for income years starting on or after 1 July 2021). This offset can reduce your tax payable to zero, but no cash refund arises. Unused non‑refundable offset amounts may be carried forward to future income years, subject to certain rules.

These rates are published by the ATO and the business.gov.au overview of the R&D Tax Incentive. You must confirm the rates that apply to your income year with your registered tax agent, because rates can change.

Proposed reform: The government has announced a change, effective from income years starting on or after 1 July 2025, that would lift the refundable offset turnover threshold from $20 million to $50 million. At the time of writing, this change is not yet law. Treat it as proposed only, and discuss its potential impact with your accountant. GrantsMAX monitors these changes and helps growing companies stay current.

Step 4: Calculate the R&D tax offset amount

Now the arithmetic:

Refundable offset example concept:
Assume a notional deduction of $200,000 and your company qualifies for the 43.5% refundable rate. The R&D tax offset would be $200,000 × 0.435 = $87,000. This amount first reduces your taxable income tax liability. If the liability is $50,000, the offset zeroes it out and you may receive the remaining $37,000 as a cash refund. (The exact outcome depends on other tax positions, carried‑forward losses, and other offsets; this is illustrative only.)

Non‑refundable offset example concept:
If the same company had a turnover above the threshold and qualified for the 38.5% rate, the offset would be $77,000. If the tax liability were $60,000, the offset would reduce it to zero, and the remaining $17,000 could potentially be carried forward to a future year (subject to continuity of ownership and same‑business tests).

The benefit you may receive is never a simple percentage of total project spend. It is a function of eligible notional deductions, the applicable offset rate, and your company’s overall tax position. The ATO’s step‑by‑step guide explains how to apply the offset in the company tax return.

Interaction with company tax rate

The R&D tax offset is not a deduction; it is a direct tax offset that reduces tax payable. Conceptually, it front‑loads a benefit that would otherwise be spread over asset lifetimes. This is similar in principle to how research credits work in other jurisdictions, such as the U.S. research credit, where qualifying expenses generate a dollar‑for‑dollar reduction in tax liability. Bloomberg Tax explains how similar mechanics apply in the U.S. While the rules differ, the idea of converting eligible R&D spend into a tax asset is a common theme.

Pro tip: Do not double‑count. If you claim the R&D tax offset, you cannot also claim a general tax deduction for the same expenditure. The notional deduction concept replaces the ordinary deduction with the offset mechanism.

Step 5: The accountant’s role, review and lodge

A critical part of the calculation is the review and sign‑off by a registered tax agent. The agent will:

• verify the eligibility of activities and the classification of costs
• check that registrations are valid and timely
• ensure the notional deduction is properly computed and apportioned
• apply the correct offset rate and complete the R&D schedule in the company tax return
• assess the overall tax position to determine how much of the offset is usable or refundable

GrantsMAX prepares a complete, evidence‑backed application pack that includes the activity narratives, cost structure pulled from your accounting data, and a supporting‑evidence index. Your accountant then reviews, refines, and lodges the claim. This division of responsibility keeps the business in control and the accountant compliant with Tax Practitioners Board requirements.

Accountants and advisors can use GrantsMAX to streamline the preparation phase, so they can focus on the high‑value review and lodgement steps.

Step 6: Prepare your application with GrantsMAX

GrantsMAX helps you build the foundation of the calculation before your accountant gets involved. Here is how the platform works:

1. Connect your accounting data (read‑only). GrantsMAX integrates with Xero, MYOB, QuickBooks, Microsoft 365, and Google Workspace to pull financial and operational data without altering your books.
2. Discover grants and incentives you may be eligible for. The AI matches your business profile against the R&D Tax Incentive, EMDG, and state innovation grants, ranking opportunities by fit. This discovery tool saves hours of manual searching.
3. Map eligible activities and costs. Using your data, GrantsMAX highlights activities that may qualify as core or supporting R&D and begins drafting the activity narratives. The system also flags risk areas a reviewer would scrutinize.
4. Draft the notional deduction calculation. The platform pulls eligible costs from your accounting ledger, salary allocations, contractor invoices, material purchases, and assembles a provisional cost structure. It cross‑references each line to source documents, building an audit‑ready evidence trail.
5. Hand over to your accountant in a shared workspace. The accountant reviews the draft pack, refines the narratives and numbers, and ultimately lodges the claim. The business owns the claim at all times.

For R&D‑active startups, this approach reduces the administrative load while keeping the accountant firmly in control. Technology companies, in particular, benefit because software engineering claims demand tight narrative‑cost linkages.

Pro Tips and Warnings

Throughout the calculation process, certain practices can make or break a claim.

Keep contemporaneous records

The ATO expects that businesses can demonstrate the connection between expenditure and R&D activities at the time the costs are incurred. Timesheets, lab notebooks, design documents, and email correspondence are more persuasive than descriptions prepared months later. GrantsMAX indexes your digital evidence automatically.

Do not double‑dip

You cannot claim the R&D tax offset on expenditure that has already been funded by a government grant that requires you to forgo the R&D benefit. Additionally, if you claim a reduced tax deduction for R&D expenditure under another incentive, the offset calculation must be adjusted. Your registered tax agent will know how to avoid common traps.

Seek professional advice early

The notional deduction amount is not always obvious. There can be borderline costs, apportionment debates, and structural questions (for example, when R&D activities are conducted through a joint venture or by an associated entity). Engaging a registered tax agent early gives you a clear scope of what to track and how to document it.

Beware of proposed legislative changes

The announced 2026 reform that would raise the refundable offset turnover threshold to $50 million is not yet law. Do not structure your business or budget around it until it is enacted. GrantsMAX keeps you informed as changes develop.

Your potential benefit is not a fixed percentage of total project spend

Many business owners mistakenly multiply their total R&D project cost by the offset rate. The actual calculation is far narrower: it includes only eligible expenditure, excludes excluded items, and interacts with your tax position. Treat any estimate as a range, not a promise.

Summary and key takeaways

• The R&D tax offset is calculated by multiplying your notional deduction (eligible R&D expenditure) by either the refundable rate (currently 43.5% for turnover under $20m) or the non‑refundable rate (38.5% for turnover $20m and above). Always verify rates with the ATO for your income year.
• The notional deduction must be supported by contemporaneous records and linked to registered R&D activities.
• A registered tax agent must review and lodge the claim; the business owns the claim, and the agent is responsible for the tax return.
• Your actual benefit depends on your tax liability, other offsets, carried‑forward losses, and whether the offset is refundable or non‑refundable.
• Proposed changes to the threshold are not yet law; monitor them but do not rely on them.
• GrantsMAX helps you prepare the evidence‑backed pack, but the accountant remains in control at lodgement.

If you are curious about what your business may be eligible for and want a prepared pack you can hand to your accountant, join the GrantsMAX waitlist today.