I don’t know about today’s arrangements, but when I served I was paid from the RAF budget (i.e. Whitehall) and my pay was credited to my bank - which remained Barclays in Witney wherever in UK I happened to serve. Tax, GP & NIS all deducted at source. Where would Scotland come into the equation? It appears that Scottish taxation is being improperly applied. (Thinks: I didn’t even pay council tax when living in or living in AMQ.)