Employees - make sure you only pay what you owe!
The tax deducted from your salary is calculated by taking away a proportion of your annual tax free allowance from your salary and applying the appropriate tax rate to the difference. Most payroll systems are quite adept at calculating the tax due, but they rely on the tax office to issue a correct code number to quantify your annual tax free allowance - this is the area where mistakes can be made and your tax bill increased unnecessarily. 
Basically the higher your tax code the less tax you will pay, and visa versa. A few common errors are:

• Employers are sometimes slow in sending in details to the tax office when new employees start. This can delay the issue of a correct code number resulting in excessive tax deductions.
• Employees who change their company cars for lower taxed models, or indeed stop using a company car will continue to be taxed based on last tax years information, unless the tax office is informed.
• The tax office will sometimes seek to recover unpaid tax in earlier years by reducing your tax code in the current year. This deduction should always be checked to make sure the arrangement does not duplicate other payments that you may have made directly to the Inland Revenue

PAYE – Issues for Employers and Employees.
Employers
As an employer, you have obligations to the Inland Revenue, which must not be ignored, else you will incur penalties! 
Most penalties arise if you either:

• miss certain statutory deadlines for remitting tax and national insurance you have deducted from your employees, or
• are late submitting returns to the Inland Revenue.