proof of very old Vat debt

 This week I received a VAT claim for £900 from VAT debt recovery, Newcastle. It dates from 2002 and includes £75 surcharge. No ongoing surcharges/ interest.

I took over sole ownership of  this consultancy 7 years ago. We now have no records from prior to this. We keep them approx 8 years. How can they prove the debt

and how can I defend the claim. I have done nothing yet. I did phone them on the number they gave me... it just rang out all day !!!

HMRC debt collection claim that they have written to us before. Absolutely not in last 7 years. They threaten sending debt collection agency (possibly a standard

threat). I have had dealings with NIC Newcastle this year.... they are a disfunctional mess/ shambles. No dept knows any other, many lost letters, emails, faxes

They finally admitted that 5 years NIC contributions were paid in 1996 !!! and uprated my personal pension records. Luckily I keep all personal NIC payments going

back many years.... but no VAT info older than 7 years

Are they just fishing?    What should I do next