My understanding of tax returns is that it is the tax payers responsibility to inform the IR that they require a tax return to fill out for whatever reason. Also, if you move house, NATS (or whoever you work for) do NOT inform the IR that you have moved, it is your responsibility.
As with everything to do with the IR it is up to you to prove you don't owe them money, not up to them to prove you do!
Happy form filling......
