Facebook is changing its tax structure in the UK. As from April its profits from advertising in the UK will be taxed in the UK. It had faced criticism due to only having paid £4,327 in corporation tax in 2014.
It's not known how much of its profits are generated in the UK but it's expected that Facebook will pay millions more in UK corporation tax.
http://www.bbc.co.uk/news/business-35724308