The table below shows the annual gross income and the total annual income tax paid by three different households in an economy.
| Household annual gross income | Annual income tax paid |
|---|---|
| £20,000 | £4,000 |
| £50,000 | £7,500 |
| £100,000 | £12,000 |
This income tax system is classified as
regressive
proportional
progressive
marginal
