U.K. taxpayers can calculate their working tax credit online using the tax credits calculator supplied at Gov.uk. The calculator, which can also figure other types of tax credits, can only calculate credits for the current tax year, as of 2015. To use the tax calculator, a taxpayer must be responsible for children, and neither he nor his partner can be subject to immigration control.
To use the tax credits calculator to calculate working tax credit, a taxpayer must provide his income, his working hours, any benefits he claims, his partner's income and the weekly amount spent on child care. The working tax credit is available to those who are 25 or older and to taxpayers under 25 who have a child or are disabled. Qualifications for the working tax credit include working a specific number of hours per week for pay and earning no more than a specific amount, according to Gov.uk. While the basic 2015 working tax credit is £1,960, the amount of the credit can be increased or decreased depending on the taxpayer's specific income and circumstances. Any change in income or circumstances typically results in a change in the working tax credit received. It's not possible, however, to claim the working tax credit and the universal credit.