An author who is not a US citizen needs to complete an online ‘tax interview’ accessible from the CreateSpace Dashboard. This is a simple undemanding form but if you do have a query simply email CreateSpace and you should have a response within twenty-four hours. When you have completed and submitted the form leave the matter for a few days and then check it has been processed by logging in to your CreateSpace Dashboard and navigating through

Accounts Section   → My Accounts   → Royalty Payment Information

Towards the foot of the royalty payment information page you should find the notification:

‘Tax Information Completed’  and the date.

Ensure that it states:  ‘Applicable withholding rate:0%’

The above means that you will avoid paying US tax on your royalties. Obviously you need to deal with the UK Revenue Service with regard to tax on your personal income including publication royalties.