Complete Guide to UK R&D Tax Relief

R&D tax relief calculator

A quick, honest sense of scale: what a claim could be worth under the merged scheme or ERIS. It is a guide, not a claim figure. The rates are current, but the base you enter is usually the part that is overstated, and only a detailed review gives a number you can rely on.

Written and reviewed by the InnoClaim team, a firm of Chartered Tax Advisers. Last reviewed 9 July 2026.

Interactive guide

Estimate what a claim could be worth

Enter your best estimate, and be conservative. Much of what looks like R&D is not qualifying expenditure once it is tested.

Before any R&D adjustment, is the company…

Prefer to work it out by hand?

The calculator uses the same three steps you can follow yourself.

Step 1: estimate the qualifying base. Not your R&D budget: the apportioned staff costs, 65% of unconnected bought-in work, consumables, software, data and cloud, less overseas exclusions. Most estimates are wrong here, not at the rate. Work from qualifying costs.

Step 2: pick the route. Loss-making, R&D-intensive SME through all three ERIS gates: ERIS. Everyone else: the merged scheme. The gates are on ERIS explained.

Step 3: apply the arithmetic. The current rates, the after-tax netting and worked examples for both routes are maintained in how much you can claim, so this page never carries a second copy that can drift out of date.

Why this is only a guide

A calculator is the most quoted, screenshotted, decision-driving page an advisory site has, and the least able to carry nuance. The rate is public; your qualifying base is not, and that is where real claims diverge from estimates. Two companies spending the same amount can claim very different figures once the costs are tested, apportioned and restricted. Treat any number here as a sense of scale, and remember that the way to know where you actually stand is a short, honest conversation with a chartered adviser.

Sources
  1. HMRC, Research and Development (R&D) tax relief: the merged scheme and enhanced R&D intensive support, gov.uk
  2. HMRC, Corporation Tax rates and Marginal Relief, gov.uk
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