Your personal allowance is being allocated against one job/pension but you actually have more than one job/pension: If HMRC are not aware that you have two employments, you may have been given the standard tax code for both jobs, and so be getting two tax free personal allowances (one against each income).
If you have more than one job as an employee, you need to check that your PAYE code is correct for each job. The same principle applies if you have more than one pension (or both an employment and pension). But this system does not always mean that you pay the right amount of tax.
When do you get a new coding notice from HMRC?
Your circumstances can change during the tax year, so HMRC can amend your tax code at any time and send you a new PAYE coding notice. Keep all your coding notices to check that HMRC have calculated your tax code correctly and that your employer is using the correct tax code for you.
What do you need to know about the coding notice?
The coding notice provides a note for every item in the tax code calculation. These notes are intended to help you to check your tax code, but the way the tax rules work means this is not always straightforward.
Can a coding notice be issued in hard copy?
There are some cases where HMRC are not obliged to issue a coding notice in hard copy, but you can still ask them for one (you will always be able to see your current coding notice in your Personal Tax Account ); and tell your employer (or pension provider) what your tax code is, but not how they have worked it out.
How to check your coding notice for taxes?
if you are employed and your employer provides you with benefits, such as private medical insurance or a company car, the value of those benefits may be taken off your tax-free amount if your employer is not payrolling them; back (for more on the adjustment that is made to collect unpaid taxes see How do I check my coding notice? below).
