Marginal Relief Calculator
Automatic marginal relief on profits between £50k and £250k — including FY1/FY2 splits and short periods
Why Use This Feature?
How It Works
Enter your trading profits and any other taxable income
Confirm the number of associated companies
TinyTax compares profits against the £50k lower and £250k upper thresholds
Marginal relief is calculated using the standard fraction (3/200)
Effective tax rate displayed alongside the CT600 boxes
Who Benefits?
Profits Between £50k and £250k
The marginal relief band where the effective rate climbs from 19% to 25%. TinyTax does the maths so you don't have to track the standard fraction or threshold scaling.
Periods Straddling 31 March
Accounting periods that straddle the financial-year boundary need profits apportioned across FY1 and FY2 with separate marginal relief calculations. TinyTax handles both halves automatically.
Companies in a Group
Associated companies share the £50k/£250k thresholds — adding more associated companies lowers your marginal relief. TinyTax adjusts for this when you set the count.
Frequently Asked Questions
What is marginal relief?
A tapered reduction to corporation tax for profits between £50,000 and £250,000. Below £50k you pay 19%; above £250k you pay 25%; in between, marginal relief tapers the effective rate. The standard fraction is 3/200.
Do I need to do the calculation manually?
No. TinyTax computes marginal relief from your profit figures, period dates, and associated company count. The calculation is shown on the CT600 preview before you submit.
How are short periods handled?
The £50k and £250k thresholds are scaled by the number of days in the period. For example, a 6-month period uses thresholds of £25k and £125k. TinyTax applies this automatically.
Where is marginal relief shown on the CT600?
Box 435 on the CT600 (2024 version). TinyTax populates it from the marginal relief calculation and shows the resulting tax due in Box 475.
Ready to Get Started?
Join hundreds of UK micro-entities using TinyTax to file CT600 and accounts
Search Your Company