Additional rate tax (also known as the top rate of income tax) is a higher tax rate that is applied to income over a certain threshold.

The current additional rate tax is £150,000 per year, this will be reduced to £125,140 from the 6th April 2023. This applies to non-savings, non-dividend income, for taxpayers in England, Wales and Northern Ireland. This will also apply to the savings rates, dividend rates and default rates which apply to taxpayers across the UK.

The current threshold for additional rate tax in the UK is £150,000 per year, and the tax rate is 45%. This means that if an individual's income is over £150,000 per year, they will be required to pay 45% tax on the amount over £150,000.

This measure does not apply to non-savings, non-dividend income of Scottish taxpayers, as the Scottish Parliament sets the Income Tax rates and thresholds for Scotland.

If an individual has an income of £180,000, the calculation for the additional rate tax would be as follows based on the threshold of £150,000:

First, we need to calculate the income that is subject to the additional rate tax: £180,000 (income) - £150,000 (threshold) = £30,000 (income subject to the additional rate tax)

Then we calculate the additional rate tax: £30,000 (income subject to the additional rate tax) x 45% (additional rate tax) = £13,500

So in this example, an individual with an income of £180,000 would owe an additional £13,500 in taxes at the 45% rate. It's important to note that this is just an example and the individual's tax liability may be different depending on their specific circumstances and deductions.

It is always recommended to check with the HMRC or a tax professional for the most up-to-date information.

Additional rate tax is typically only paid by high-income earners, and it is one of the highest tax rates in the UK.