From some of the foregoing posts it is obvious that the Inland Revenue are indeed targeting the military. The reason being that they discovered your Pay Accounts professionals have failed to administer their PAYE responsibilities properly and many of you seem to have been underpaying your tax.
I'd recommend you get professional assistance with any large tax demand - the fees for an accountant to check your tax returns are generally covered by the savings they make. Especially on bills for several thousand pounds back dated for a few years.