Any of the discussions on tax bring us back to the three areas of possible taxation.
Earned Income
Passive Income
Wealth.
Each is treated differently, with different tax rates, reliefs, and philosophies behind them. Tax on earned income, i.e., tax on employment income (salary, wages, bonuses, benefits in kind), self-employment profits and some short-term contractual or gig work, comes from Income tax and National Insurance. Although often described as “contributions”, NICs function largely as an additional tax on earned income, not on investment income. Earned income is the most heavily taxed category overall.
Next we have Passive Income or investment-derived income. This includes Dividends, Interest (savings, bonds), Rental income, Capital gains (on disposal of assets). This tax is on the income earned on invested capital not, as some seem to think, on the already taxes Capital. Although tax in these areas is generally relates to marginal income passive income is generally taxed more lightly than earned income, and NICs do not apply.
Lastly Wealth. The UK does not have a comprehensive wealth tax. Instead tax is triggered at certain points.
To summarise:
Earned Income has the highest relative tax burden - heavily taxed via Tax and NIC
Passive Income has a medium relative tax burden - taxed but on lower rates and no NIC
Wealth has the lowest relative tax burden - taxed only at specific events.