Autumn Budget 2026 and R&D Tax Relief: What to Watch on 28 October

The Chancellor will deliver the Autumn Budget 2026 on Wednesday 28 October. For any UK company running an R&D tax relief claim — or planning its first — it is worth knowing what is genuinely on the table before the red box opens, and what is simply noise.

The short version: after three years of near-constant reform, the R&D regime is finally settling. Most of what matters for your next claim is already law. But a Budget always carries the risk of a technical tweak, and there are a few signals worth tracking.

Where the R&D rules stand going into the Budget

The big structural change is done. The merged RDEC scheme is now the default for accounting periods beginning on or after 1 April 2024, replacing the old separate SME and RDEC regimes. It gives a taxable expenditure credit of 20% of qualifying R&D costs — worth roughly 15% net once Corporation Tax at 25% is applied.

Loss-making, R&D-intensive SMEs are the exception. If your qualifying R&D is at least 30% of total expenditure, you may instead claim under Enhanced R&D Intensive Support (ERIS), which offers a more generous deduction and a payable credit for surrenderable losses.

None of this is up for debate on 28 October. The framework is set. What a Budget can still change is the detail around the edges — rates, thresholds, and how HMRC administers claims.

What the commentary actually predicts for R&D

Reading across the pre-Budget analysis from the major advisory firms, the consistent message is stability, not upheaval for R&D specifically:

• Corporation Tax looks steady. The headline rate is capped at 25% for the current Parliament, which anchors the net value of the merged credit.
• Investment incentives are expected to stay. Permanent full expensing and the Annual Investment Allowance are both flagged to remain in place — relevant for R&D-heavy firms investing in plant and equipment alongside their development work.
• No trailed changes to R&D rates or eligibility. As at the 2025 Budget, R&D relief drew little direct attention beyond minor technical adjustments. Nothing currently points to a shake-up of the merged scheme or ERIS.

The honest caveat: commentators are also calling this one of the harder Budgets to predict, with little policy leaked in advance. A quiet technical change to R&D — the kind that lands in the fine print rather than the speech — can never be ruled out. That is exactly why the administrative rules below matter more than any headline.

The compliance deadlines that will not wait for the Budget

Whatever the Chancellor says, two administrative requirements already catch companies out — and neither is going to be relaxed by a Budget:

1. The Claim Notification deadline. For accounting periods beginning on or after 1 April 2023, new claimants (and any company that has not claimed in the previous three years) must notify HMRC of their intention to claim within six months of the end of the period of account. Miss it and the right to claim for that period is lost entirely. See our guide to the Claim Notification deadline.
2. The Additional Information Form (AIF). This is now mandatory for every R&D claim and must reach HMRC before, or on the same day as, the Company Tax Return.

If you are unsure how much time you have left to claim for an earlier period, our guide on how far back you can claim R&D tax credits walks through the two-year window.

What to do before 28 October

• Don't wait for the Budget to start your claim. The rules for your current period are already fixed. Delay only risks the notification and filing deadlines above.
• Check your first-time or lapsed status now. The Claim Notification trap is the single most common way companies lose an otherwise valid claim.
• Plan for HMRC scrutiny. Compliance checks remain high. A well-evidenced claim, filed correctly, is the best insurance regardless of what changes — see what to expect on HMRC processing times.

We will publish a short reaction piece once the Budget lands on 28 October, covering anything that genuinely affects R&D claimants. If you want that read applied to your own position, get in touch.

Frequently Asked Questions

When is the Autumn Budget 2026?

The Autumn Budget 2026 will be delivered on Wednesday 28 October 2026. Any measures affecting R&D tax relief would be announced on the day, with legislation typically following in the subsequent Finance Bill.

Will R&D tax relief change in the Autumn Budget 2026?

No major change to R&D tax relief has been trailed ahead of the Budget. The merged RDEC scheme and ERIS are already in force and the pre-Budget commentary points to stability. A minor technical adjustment is always possible, but the core rates and eligibility rules are not expected to move.

Should I delay my R&D claim until after the Budget?

No. The rules for your current accounting period are already law, and waiting risks missing the six-month Claim Notification deadline or the deadline to file your Additional Information Form. It is almost always better to progress a claim than to wait for the Budget.