Chancellor Rishi Sunak on windfall taxes on oil and gas profits

Windfall taxes are "not the simple easy answer" to every problem, the chancellor has told MPs.

But Rishi Sunak warned oil and gas firms if they did not invest some of their "extraordinary profits" into British jobs, growth and energy security "soon and at significant scale" then he would not rule a windfall tax out.

How would a windfall tax on energy firms work?