I think the tax threshold should be higher for sole traders, there is no encouragement from the government for you to invest and grow your business.
I think maybe the threshhold should be higher for everyone.
However, perhaps there is a case for it being lower or non-existent for very high earners as the extra tax paid would be a smallish amount compared to total income (when NI and 40% tax are factored in the yearly bill would be about £2,500 more if totally abolished for very high earners). The drawback to this is that the tax threshhold is set before the annual figures are known.
Basically, what I'm saying is that everyone else should be taxed a bit more so that I can be taxed a bit less

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I see a poll has been added. I feel that non compliance would be a step too far. It would have to get a lot worse before I would consider that when you bear in mind that the state could bankrupt you and make you homeless with great ease.