Each year between January and March, HMRC issue tax code notices to some individuals for the new tax year that starts in April.  HMRC issues a tax code notice so that an employer will deduct the correct amount of tax through the payroll. 

HMRC issues a detailed calculation to the individual and a summary notification to the employer to use the tax code from a specified date. 

It is always worth checking that the information shown on the tax code notice is correct and that there are no items missing or incorrect figures.

If you believe the calculation is wrong then phone HMRC (Tel: 0845 300 0627) to discuss the figures that may be incorrect.  If for example you have a company car and it is not shown on the calculation by HMRC, you will not have sufficient tax deducted from your pay and will end up with a tax liability to pay at a later date unless the tax code notice is amended by HMRC.

At any time during the tax year, HMRC may issue a new tax code notice to an individual which will supersede the existing tax code used by an employer.  The intention of HMRC is to issue the correct tax code to ensure that employees have the correct amount of tax deducted from their income.