Im 16, need help with my wage slip. UK Only.?

-I gave my p45 forms in in march. On a wage slip from April my tax code was 647L and no tax (tax TD) was paid. i changed my bank account a few week later, and in a wage slip from june it says my tax code is BR and that ive paid tax TD :( Why did this happen and what can i do to stop paying tax.You have not kept your address up to date - somewhere there is a "notice of coding" making it's way back to the tax office. So write or phone HMRC (address and number on the website). Is this your only or main employment? Your main job gets the tax allowances (7475 now or code 747L).

Other income? HMRC clearly thinks you have another source of money.
You or your employer should call your tax office, You are currently on emergency tax and you need to get that sorted, any tax they have deducted will be given back.
Find your nearest local tax office and speak to someone there about personal taxation. You should find your office in the yellow pages or at http://www.hmrc.gov.uk