Confusion over tax codes - help!

Clarey22

Hello, am hoping someone with more of a brain than me can help. My husband is due to leave the army after 14 years service next month and has been contacted by the pay office to say he is currently on the wrong tax code. They said he is on tax code 653L and it should be 647L. I have pulled out his previous P60's and they all have different codes going back over the last few years. Have tried using the tax calculator but am confused.com and hoping someone can shed some light as to whether he not paid enough tax over the last few years so we can prepare ourselves for a letter from the taxman.

Previous tax codes on P60:
2009/2010 - 653L (told should be 647L)
2008/2009 - 609L
2007/2008 - 508L
2006/2007 - 508L
2005/2006 - 494T (what does T stand for?)

Thanks for any help.

Caz3121

he should have received a letter from the Inland Revenue each year showing him how his tax code is calculated

not sure about the historic data but for this year a tax code of 647L means you can earn £6475 before paying tax...looks like they have given him an extra £60 per year within his allowance for some reason (should be explained on the tax letter re the code)
worst case he is due the tax on this additional amount - even if he was a higher rate tax payer this would be around £25