Oh, and by the way the plan for a flat rate of taxation is about as sensible as Farage usually is (ie not at all) in that while there is a reasonably consistent way to measure employment income in many cases, without limitation: -

(a) there is no easy way to determine income other than from employment (eg income from self-employment and unearned income);
(b) there is no easy way to determine chargeable capital gains;
(c) there is no easy way to determine accumulated earnings in companies, if it is not paid out as dividend or salary;
(d) there is no easy way to be sure that deductions are fair;
(e) there are always allowances, and accountants can manipulate them;
(f) in multinational cases, ensuring proper jurisdictional attribution is very hard.

Imagine the howl from the rich if pension payments were not deductible.

Farage's tongue ran away with him there (but then that has happened before). The man is more of a buffoon and an even more of a detestable character than Boris Bloody Stupid Johnson.