I have been on a month 1 week 1 tax code since April 07?

I really think I am paying too much tax to HMRC.
I have been on code 152LM for ages now, so can I get this
changed - if so how - and will HMRC give me my money back
next April?

Thanks for your answers.

Hi - no other income no, so don't know why I am paying so much tax - maybe I am paying the same as everyone else, but my gross salary is 拢20k, I have a company car and am taxed on that, and I have been with the same comapny for 7 years.

The tax does seem excessive.

The code number restriction for your car is based on the information your employer sent in on your last form P11D, for the tax year 2006/2007. You would have had a copy. If you compare this with your notice of coding (form P2), you will see if the restriction is correct.
If your car has changed in the year, the benefit may be different. Your tax situation will be reviewed if car details different, but if your car has been updated, you are as likely to be underpaid as overpaid.
The Government is really clobbering people who have company cars now.

Usually, once you complete a P46...
Or have produced a P45
The HMRC informs you of your new tax code.

Do you have other income? If not you need to contact HMRC to correct your coding.

If you do have other income you'll need to fill out a tax form at the end of the year so HMRC can assess your income and tax due. They will not do this automatically so you'll need to contact them.

Sorry I can't really help without all the details.

Your code number takes into account the car benefit, so the tax due on your company car is being collected monthly through your PAYE code number. Without knowing your car details, I can't tell if your code is right, but in general, it looks right to me! You will need to phone HMRC for an explanation of how the car benefit is worked out.
You are on a week 1 basis as I imagine the car benefit was included in your code once the tax year had started. This means that the tax is spread throughout the year rather than being deducted in the month the code came into operation. You will only have overpaid tax if the incorrect car benefit is included in your code, for instance if you change to a cheaper car or lose the car part way through the year.