I, too, have received one of these letters today. Concentrix cannot tell me who I'm supposed to be living with - Data Protection of course.
Took me ages to get through on the phone to them, but they said I can printout my online bank statements, and it's also okay that they show things like mortgage and utility bill costs on them (I have no paper bills).
I don't like the idea of them trawling through my bank statements either, but you have so little time to do anything about it before they'll stop Tax Credits, that I guess I will have to send them on (all 23 pages of statements).
I suspect my ex-husband is using this address and this is what has triggered the Concentrix letter, although it could be my 17-year old son applying for a driving licence. Either way, it's very annoying.
On the plus side from today's conversation with Concentrix, I got some positive information regarding 'debt threat letters' addressed to my ex-husband here (he left in 2005). One, received last year, said that some "new information" had come to light that made the company that were writing to him think that he was living at my address. Of course, under Data Protection this company refused to tell me what this information was.
Anyway, it turns out that you can write to HMRC and request a 'Subject Access Request' to find out who is connected with your address, and HMRC will divulge any info they have. HMRC confirmed this to me and they require the following info:-
Exactly what you want to know
Your full name (+ any maiden name)
Current address and any other addresses in the last 5 years
Date of birth and NI number
If self-employed your UTR number (Unique Tax Ref)
If employed employer's details
Child Benefit number
Send this info to:-
The Tax Credits Processing SAR Team
Floor 1, Area E
St Mark's
PRESTON
PR1 4AT
I hope the above will be of use to some of you.