What is the UK Corporation Tax rate for 2026?

For the 2026 financial year, the UK main rate of Corporation Tax is 25 percent, applicable to companies with taxable profits over 250,000 GBP. A Small Profits Rate (SPR) of 19 percent applies to companies with profits below 50,000 GBP. Companies with profits between these two figures pay the main rate but can claim Marginal Relief to bridge the gap, resulting in an effective sliding scale rate.

How does the unified R&D tax credit scheme work in 2026?

The unified R&D intensive scheme merges the former SME and RDEC programs into a single framework. Under the 2026 rules, most companies receive a taxable expenditure credit. However, R&D-intensive loss-making SMEs (where R&D spend accounts for at least 30 percent of total expenditure) can access a higher rate of relief via a payable credit. Effective documentation of scientific or technical uncertainty is mandatory for all claims.

What are the UK Corporation Tax payment deadlines for 2026?

Small and medium companies must pay their Corporation Tax within nine months and one day after the end of their accounting period. For example, if your year ends December 31, 2025, payment is due October 1, 2026. Large companies with annual profits exceeding 1.5 million GBP are subject to the Quarterly Instalment Payments (QIPs) regime, requiring payments in months 7, 10, 13, and 16.

Can I still claim Full Expensing for UK capital investments in 2026?

Yes, Full Expensing remains a permanent fixture of the UK tax code in 2026. This allows companies to deduct 100 percent of the cost of qualifying plant and machinery from their taxable profits in the year of purchase. There is no cap on the amount of investment that qualifies, making it a powerful tool for capital-intensive startups and manufacturing firms.

What is the current UK Small Profits Rate threshold?

The Small Profits Rate of 19 percent applies to UK companies with annual augmented profits of 50,000 GBP or less. If a company is part of an associated group, this 50,000 GBP threshold is divided by the number of associated companies. For example, if two companies are under common control, the threshold for each drops to 25,000 GBP to prevent profit splitting.

2026 UK Corporation Tax Guide: New Rates and R&D Credit Reform |…

TL;DR: In 2026, the UK Corporation Tax main rate remains at 25 percent for profits over 250,000 GBP, while a 19 percent Small Profits Rate applies to companies earning under 50,000 GBP. Businesses must navigate a unified R&D credit scheme and utilize permanent Full Expensing for capital investments to optimize their tax liability.

Understanding UK Corporation Tax in 2026

Navigating the UK Corporation Tax landscape in 2026 requires a firm grasp of the tiered rate structure and the specific reliefs designed to foster innovation. All UK-resident companies are liable for corporation tax on their worldwide profits, which includes trading profits, investment income, and capital gains. Non-resident companies are generally liable only on profits tied to a UK permanent establishment or UK real estate.

Since the landmark shifts in fiscal policy over the last few years, the UK has maintained a competitive but structured tax environment. The system is designed to reward high-growth, high-investment entities while ensuring small businesses retain a greater share of their early-stage revenue through the Small Profits Rate.

Modern office building in London financial district

2026 UK Tax Rates and Thresholds

The 2026 financial year continues the dual-rate system. Your total liability depends on your "augmented profits," which include taxable profits plus any exempt distributions received from non-group companies.

Profit Level	Tax Rate	Relief Category
0 to 50,000 GBP	19%	Small Profits Rate (SPR)
50,001 to 250,000 GBP	25%	Main Rate with Marginal Relief
Over 250,000 GBP	25%	Main Rate

The Marginal Relief Mechanism

For companies earning between 50,000 GBP and 250,000 GBP, HMRC applies a "Marginal Relief" fraction. This ensures that the tax rate increases gradually from 19 percent to 25 percent. This prevents a “cliff edge” effect where earning one extra pound would drastically increase the tax burden on all previous earnings.

Associated Companies Rule

It is vital to note that these thresholds (50,000 and 250,000 GBP) are divided by the number of associated companies under common control. If you operate three distinct UK entities, the upper threshold for the 19 percent rate for each entity would be 16,666 GBP.

R&D Tax Credits: The 2026 Merged Scheme

By 2026, the transition to the unified R&D tax relief scheme is fully mature. This merged scheme replaces the previous distinct paths for SMEs and large companies (RDEC), creating a streamlined process for all applicants.

The Merged Expenditure Credit

Most companies now claim under a system similar to the old RDEC. The credit is calculated as a percentage of qualifying R&D expenditure and is recognized as taxable income, which simplifies accounting and provides an above the line benefit. This is particularly useful for companies that are not yet profitable but are investing heavily in technical breakthroughs.

R&D Intensive SME Support

There remains a specific carve-out for R&D-intensive small businesses. If your R&D spending accounts for 30 percent or more of your total expenditure, you may be eligible for a higher rate of payable credit. This is a critical lifeline for biotech, deep tech, and AI startups where early years are defined by high research costs and zero revenue.

A tech founder working on a laptop in a bright workspace

Capital Allowances and Full Expensing

A major pillar of the 2026 UK tax strategy is the permanent status of Full Expensing. This allows companies to deduct the entire cost of qualifying plant and machinery from their profits in the period the expense is incurred.

Qualifying Assets

Main Rate Assets: This includes machinery, office equipment, and even some furniture. These qualify for 100 percent first-year allowances.
Special Rate Assets: Items like electrical systems or solar panels qualify for a 50 percent first-year allowance, with the remaining balance written off in subsequent years at the standard 6 percent rate.

This policy encourages businesses to upgrade their infrastructure and adopt new technologies without waiting years to realize the tax benefits through traditional depreciation models.

Compliance and Filing Deadlines

UK tax compliance is governed by strict digital reporting standards under the Making Tax Digital (MTD) initiative. In 2026, most businesses must keep digital records and use MTD-compatible software for their filings.

Key Compliance Checklist

Register for Tax: You must register for Corporation Tax within three months of starting to do business.
Annual Accounts: Prepare a Company Tax Return (Form CT600) and statutory accounts annually.
Filing Deadline: Your CT600 is due 12 months after the end of your accounting period.
Payment Deadline: For SMEs, payment is due 9 months and 1 day after the accounting period ends.
Quarterly Payments: If your profits exceed 1.5 million GBP, you must pay in four quarterly instalments starting in the seventh month of your financial year.

How Gullia Filing Helps

Gullia Filing provides end to end support for UK business owners, ensuring your company remains compliant with the latest HMRC regulations. From initial company formation and VAT registration to managing complex R&D tax credit claims and annual CT600 filings, our specialists handle the administrative burden so you can focus on growth. We ensure you maximize available reliefs like Full Expensing while avoiding late filing penalties.