It is important to ensure that your PAYE code is correct as you might not be paying the correct amount of tax. For the 2014-15 tax year, HMRC have a new facility which could save you the hassle of ringing HMRC and facing a potentially long wait on hold waiting to speak to someone, after you have negotiated the telephone menus. They have now introduced an online form through which you can notify HMRC if you think your PAYE coding notice is wrong.
When correcting an incorrect PAYE code using this form you will need to provide details of your salary, company/personal pension, state pension/benefits, company benefits and other income in addition to some more basic information. To do so, you can go to https://online.hmrc.gov.uk/shortforms/form/P2?dept-name=&sub-dept-name=&location=43&origin=https://www.hmrc.gov.uk. You will then receive an email from HMRC to acknowledge that they have received your request.
You should then hopefully receive an email within 15 working days to notify you that HMRC have updated your PAYE coding. However, if there is an issue with the coding or HMRC require further information and they are unable to contract you by telephone then they will write to you to request this.