Although it is true that CB is only paid to one parent, where there are
more than 1 child one of the "elements" can be paid to the other parent,
particularly in cases where care is shared or where there is a shared
residence order in
place.
This leads to scenarios where both parents make claims
against the other.
If you look at the legislation and the legal
criteria which defines a NRP and a
PWC, there is no mention of CB!!
One can
only assume that this "differencial" is simply a "calculated assumption",
that is, the mother, who usually is the PWC, would also be the recipient of
the CB.
I suppose it is down to the other parent (NRP) to stick
up for themselves and challenge the CSA.
Sadly there are
many,many cases where the
PWC (recipient of C

isn't the parent with whom the children are most of
the time but is the parent who is receiving CB and therefore antitled to
claim CM.
When high tax payers lose CB there will be many
"upsets" especially in cases where the NRP, who up until that point could
not claim CB, will suddenly find themselves elegible for that benefit (if
they are within the right salary range) and therefore could then become PWC
with the ability to claim against their ex's who previously were the
recipients of the CB and CM even when the children spend more time with
them.
Even now, the CSA cannot "box" cases where there is a
shared residence order because these orders, legally, define both parents
as PWC according to the current legal criteria.
It's a mess and
will only get worse after January 2013!!