When your business moves offices, you are legally obliged to tell HMRC.
Failure to do so can lead to practical problems, such as if tax post is returned to HMRC or an HMRC Officer calls to find that you have left the premises.
If this happens, HMRC may designate your business as a 'missing trader' and de-register you on 'revenue protection' grounds. In effect, this can prevent you from continuing to trade, particularly if your VAT number is withdrawn.
Although it is possible to have your business reinstated, this can be a lengthy process.
So, if you are moving premises, make sure that you notify HMRC; this includes the VAT, PAYE and Corporation Tax sections. You should also check a few weeks later to make sure that HMRC have updated your details.