Chil - you know better than that, there is no middle income trap. It is nothing like the very real trap that ChasingSquirrels and many more are in - and if you add in child care costs it is very very hard to find work that pays.
At the threshold you pay a bit more tax on the next £10 - you still get to keep the same amount of the previous £10. There is nothing wrong with that.
Of course you might be talking about the tories' stupid change to child benefit - would have been much fairer to women in particular to have decreased the higher rate threshold instead so that people are paying a bit more income tax in a fair way effectively cancelling out their child benefit.
I agree with KatyMac - a proper universal benefit / credit would be a great move. IDS has attempted this but again the child benefit change does the opposite. How unjoined up can you get. But you still need banded tax - charging a flat rate above this would be really regressive.
Chil - yes regressive means unfair and yes a change which would involve simultaneously clobbering the poor and looking after your rich mates would not look very good. But you could simplify by combining tax and NI into one without having a single rate. It is clearly fair that those on larger incomes pay a bigger proportion of their income in tax - they can afford it.
Here are some figures at current tax+NI rates of what percentage of gross income is paid in tax+NI:
£5,000 0%
£10,000 12%
£15,000 18%
£20,000 21%
£25,000 23%
£30,000 25%
£35,000 26%
£40,000 26%
£50,000 28%
£60,000 30%
£70,000 32%
£80,000 33%
£90,000 34%
£100,000 35%
£110,000 37%
£120,000 38%
£140,000 38%
£160,000 39%
£200,000 42%
£250,000 44%
£500,000 47%
calculated using www.uktaxcalculators.co.uk/
Nice smooth curve (although it wouldn't be if the new child benefit was in there). Gentle rise at the top - stop complaining rich people. I'd like to see it more gentle at the bottom.