05/07/2026
SPOTLIGHT ON: Associated company rules: Protecting your corporation tax thresholds
Running more than one limited company is common for many owner-managers. You might have a trading company alongside a property company, a separate company for a different service line, a holding company above the group, or an old company kept for a brand name.
Each company may have made sense when it was set up. The issue is what happens when the corporation tax rules look at those companies together.
Since 1 April 2023, the UK has used a tiered corporation tax system. The thresholds that decide whether a company pays the 19% small profits rate, the 25% main rate, or a rate (due to marginal relief) between the two can be divided between associated companies. The more associated companies there are, the lower each company’s thresholds become.
This guide explains how the rules apply to accounting periods falling within the corporation tax financial year starting 1 April 2026, who counts as an associated company, and the practical steps that can help protect your position.