I was offered permanent WFH last year and turned it down. I don’t normally have any commuting costs as I have private fuel as a BIK which I am taxed on, I have a parking space at work. I am still paying tax on my fuel as if I cede this benefit I will never get it back. I sometimes buy a lunch, but often have leftovers, as I am at home.
So I am potentially saving about £10 a week on lunches =£460 a year, (6 weeks holiday a year) but I would pay an additional £5,000 a year under this proposal. If I give up the fuel benefit, I would pay about £2k a year less tax, but have to pay for the fuel I use.
I am paying more for heating etc at home, but it is my employer saving office costs (if able to down size offices, which currently Social distancing is preventing).
I do expect tax rates to increase to cover the costs of COVID, my husband received furlough pay for 3 months earlier in the year, and is furloughed again, but to charge me for WFH when I have declined it previously would not be acceptable.