No it's not. It's the company's obligation to pay it, if it wants to operate in the UK and have British workers.
An obligatory company tax is not part of an employee's 'package'... It's ridiculous slave mentality to think that.
That's the sort of nonsense I'd expect from a Complaints Clerk rather than someone with a basic economic background - even the government website classes it as part of an employee's remuneration albeit paid for by the employer

