At least I think it isn\’t. Mr. Chakrabortty:
The £290m fine slapped on it by regulators is tax-deductible, making it equivalent to just 13 days\’ profit.
HMRC says that fines and penalties are not deductible:
A fine incurred as a result of a trader\’s infraction of the law is not allowable on the authority of CIR v Alexander von Glehn Ltd  12TC232, as it is not incurred wholly and exclusively for the purpose of the trade.
Now tax law is a lot more complex than I am going to find out with a quick Google. So could someone confirm this?