How to declare bank account switching bonus?

I am a UK resident US citizen.

This year I have switched a couple of bank accounts and will have something like £400 in switching bonuses. Do I need to declare this as income? Does anyone know if they are paid pre-tax or post-tax in the UK?

Similar question for monthly payments. For example Halifax gives £5 a month for the bank account (not really interest, but that is after UK tax is paid I think) and £5 a month for the credit card. I guess the credit card payment could be considered cashback which I understood was not taxable in the US.

Probably not too important but trying to do things properly...

If it was a US bank then I believe that it is taxable so I would also assume that a signing bonus for a UK bank would also be taxable.

http://www.clarkhoward.com/signing-bonuses-credit-cards-being-reported-taxabl

"But here's the rub: The banks are now reporting your bonus to the IRS as taxable income."

Yes, sounds like "Other Income" 1040, line 21 to me.

From a US perspective it is other income; probably (but arguably) passive basket.

The UK treats Halifax's £5 as interest net of 20% tax (until next April) so I'd probably be consistent with local law on a US return.