If, for example, you think a 10 per cent increase in gross pay is worth 10 per cent in take-home pay, think again.
Income tax and national insurance levied in the UK are both progressive — meaning the percentage take goes up the more you earn.
And, if you are running a tight household budget, it may make a difference, especially if you are trying to save a few pounds a week for a particular purchase.
For example, to see how much you would be getting if you went down to a four-day week, either by choice or because you were forced to do so by family circumstances or other pressing needs.
You are seeing a snapshot of an interactive graphic.
This is most likely due to being offline or JavaScript being disabled in your browser.
For most people, the progressive tax system means that a 20 per cent reduction in gross pay will deliver a smaller decline in net pay.
This matters because different people spend their money in different ways.