In the UK for a two years

[dedalus]

Hi,

After being resident in the uk for just over one tax year I filled in a tax return to the HMRC.
My uk income was less than 5k and most of my assets are abroad. I claimed dual residency and under the tie break
claimed that I was resident of the overseas country for tax purposes. They wrote to me saying I do not owe anything in tax.

My situation is fluid, I am planning to leave the uk in early 2103 so this means that for a second year I will have been a uk resident.
My uk income is still less than 5k.

My questions are as follows:

a) can I just write to hmrc before oct 2012 telling them that as my income has not changed I understand i do not have to resubmit a tax return?

b) If I decide to leave earlier do I need to tell HMRC? Basically do they chase for subsequent tax returns for following years even if uk income is negligible?

Thanks