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UK Self-assessment tax calculator

UK Self-assessment tax calculator


Tool for estimating income and national insurance tax for self-employed workers in the UK. The calculator can be adapted to other tax juristictions



A tax summary table including taxable profits, taxes owed (income taxes and national insurance), effective tax rates, take home pay annually, monthly, weekly and daily



The model has a monthly timeline that runs for one year

There is an annual summary

A flexible model start date



The ability to update the model units


Tax assumptions

Income tax rate thresholds including personal allowance, basic rate, higher rate and additional rate. The user has the ability to set the tax rates and the level of each threshold. Furthermore they can set any changes to the personal allowance above a certain income level. This can be adapted for other tax juristications

National insurance - class 2 and class 4 are a proxy calculation for the UK national insurance for sel-employed income. These calculations can be adapted. However, the crrent assumptions includes the threshold for these national insurance taxes as well as the rates


Income and allowable expenses

Includes up to 11 different income lines, multiple different business costs and various costs that might be split between business and personal use



The template uses cash basis accounting (i.e. record income and expenses when paid rather than when accrued). It is up to you as the individual to ensure that you pay the right amount of tax and keep appropriate records. We strongly recommend that you seek advice from a qualified financial professional. This tool does not take into account all aspects of all UK sole trader tax legislation so should be used as a guide only.


  • T&Cs

    Refer to T&Cs page for the Terms and Conditions of the sale

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