A very much simplified tax system would be a good start.

Try a single tax on income or earnings of any kind above a reasonable threshold, say £10,00 a year.

If you recieve money, you pay the same rate of tax on it if it's from your job, the 3.30 at Newmarket at 20/1, goverment benefits, the sale of your house, anything at all. No loopholes of any kind. The inverse also applies. This is the only tax on income you pay.

Would make it rather harder to get away with financial tricks, and would allow most people to do their own taxes, and get them right easily!