Council tax: do ALL people in the house need to be declared?

CIS

So is there a legal rqmt on moving into a property to list all (adult) occupants?

Not as such, that's one of the (most obvious) loopholes that makes council tax administration difficult.

Surely most people just ring up/write etc (eg a wife for example) and say "I've moved in. Please send me a bill" or similar? And the council register her name and send out a bill?

In most cases yes, but a good staff member would ensure that they collected as many details as possible of the occupants so that they correct liability and entitlement to any discounts can be determined.

olly300

I've been in that situation more than once.

I actually used a relation's address as my correspondence address and was registered for everything there.

Due to lack of space in that relation's household I mainly stayed with a friend walking distance away. I did have some post come to that friend's house but nothing official.

I also made sure my car insurance had both my relation's and friend's addresses noted on it. (I specifically chose a car insurer who didn't have problem with someone staying in different houses a few days a week.)

In regards to your friend C moving temporarily into place and not being registered for council tax - if they didn't pay rent or contribute towards bills, and there were two people living in that household they were clearly a guest.

The concept of a "guest" confuses lots of authorities and utility companies. It also screws up your credit rating so the best situation is never to use the address you temporarily stay at for less than 3 months as an old address.