We've been discussing banking practice and the issue of them taking benefit payments to reduce overdrafts.

Is there anything in the regs which relates to this ?

I've never used it but I'd imagine that writing to the banks to try to protect these payment by using the first Right of Appropriation is a very cumbersome way of going about things.

The CAB answer to this problem (which applies to earnings as well as benefits) is to open a basic bank account (with a totally different bank) to receive income so that it does not get into the hands of the first bank.

This has nothing to do with benefit law but to the terms and conditions of the contract with the bank, to which their customers have signed up (in theory anyway). This right to appropriate to the oldest debt first and to any loans taken out with the bank is a pretty standard term. Without the security it gives, interest rates would have been much higher, historically.

I have heard it argued that s187(1) Social Security Administration Act 1992 prevents banks from taking benefit payments toward their debts as it amounts to an assignment or charge on a benefit payment. However, in practice this is only going to be of use after the event and doubtless will have to involve correspondence with the bank's lawyers (those fine people who legitimised hedge fund trading).

As Ariadne says, a basic bank account with another bank to receive benefit payments is the best option and prevents this problem from arising in the first place (and many claimants find it helps them to better manage their money). Post Office Card Account is useful in such situations.

There was a Scottish case concerning arrestment.
http://www.consumeractiongroup.co.uk/forum/general-debt-issues/87560-bank-account-arrestment.html

Arrestment is a particular method of debt enforcement available under Scots law and administered via the Sheriff Court. It should therefore rightly fall foul of s 187 SSAA. This is different from the situation where the bank just helps itself to the money paid into the account.

Sorry you may well know this already, just wanted to make this clear to people who are not familiar with Scots law.