If they did this it would raise billions of pounds - while avoiding raising taxes on working people. Exemptions should be put in place to protect small businesses; I accept this would be complicated, but they need to try and make it work.
So much money could be raised and it would also encourage earlier wealth transfers which would stimulate the economy. In addition, it would help redistribute wealth thus reducing inequality.
There would be political backlash, of course, but they need to get the economy growing and should act now so that the results are visible in time for the next general election.