Incorporating information from a US tax return

There is trust and property income on the US 2011 return, with attendant tax paid.

Given the difference in accounting periods, how do I show this on the UK 2011/12 one. Do I report 25% on a re-opened 2010/11 return and 75% on 2011/12?

And given that there will be more income on the US 2012 return, do I show figures and being estimated and have to wait until December 2013 to amend the figures?

How do you normally manage this?