AFAICT, WTC depend not merely on your personal income, but also on whether you are single or in a couple (only one of you can receive it, and your household income is what's assessed), how many hours a week you work (must be at least 30 if you're over 25, or 16 hours if you're younger), whether you have a disability, whether you're claiming any other benefits... So I doubt you put it on that graph in a straightforward way - you'd need a whole slew of graphs for different options.
But if you want to play with some different possibilities, this site might be helpful:
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Date: 2007-03-22 08:22 pm (UTC)But if you want to play with some different possibilities, this site might be helpful:
http://www.taxcredits.inlandrevenue.gov.uk/qualify/WhatAreTaxCredits.aspx
(link to calculator at the bottom).