How can i get my p45 if they said they sent it to my previous address?

last march when I finished work the agency I was working for said they sent my p45 to my previous address, actually I never got it and I need it...they said they can not make another copy for me.....so I do not know how to do

The agency may sound like they're being a bit bureaucratic about this but it's true - only one P45 can be issued by an employer even if the original gets lost in the post. The reason for this is that each individual is given a 'tax code' by the Inland Revenue. This code (in the vast majority of cases) allows you to recieve a specific amount of tax free earnings in your pay. If more than one P45 is issued then this code will be duplicated and could allow an individual to use the tax free allowance more than once - hence doubling (or more) the amount of pay you can get in a year without tax. The net result; great big under-taxation.

So...

Ask your new employer for a P46. This is the form that must be completed in the absence of a P45. It's a simple tick box sort of form that allows a new employer to provide you with a temporary tax code. The form then goes off to the tax office who examine your records and tell the new employer precisely what code you should be on (via a form called a P6). It's straight forward but can take a while so it's well worth chasing the relevant tax office (ask employer for contact phone number and their tax office reference number) to ensure that everything takes place as promptly as poss.

If you only need just the info from the P45 (for instance, if you're filling in a tax credit application) then just ask the former agency for a 'statement of earnings' and explain why. Alternatively, look at the last payslip that you recieved off them and you'll have your final earnings detailed on it.

On no account break into your previous address under the cover of night. It's illegal and really scary for whoever lives there now.