Having a bit of a dense day here. Can anyone point me to the regulation that states that arrears of PC are not treated as income/capital until they are actually received?

And does this disregard apply only to someone already in receipt of HB/CTB? Just had a decision where a PC and HB/CTB claim were made at the same time and both backdated for 12 months. SC was taken into account as income for the whole of the backdate period rather than from when it was actually received. I seem to be having a mental block about this (pretty normal for a Friday). I had previously assumed that any payment of (PC)SC was only taken into account from when it was received regardless of whether this was in relation to an exisiting HB/CTB claim or a new/concurrent one.