tax credits were what came after working family tax credit
working family tax credit came in septemebr 1999 and meant for the first itme that if you came o benifit and went into work you could have your wages topped up if they were low and you could also have 70% of your childcare paid for if you were a single mum.
This was a great incentive to get single mothers back itno work as they had always complained if they worked they were worse of than claiming unemployemtn benifit as they needed to pay for childcare and petrol cost.
The working families tac credit was based on 6 weeks wage slips and claimed every 6 months and paid through your wage slip by your employeer.
You coudl as a single mother also claim the married mans tax allowence - so you got an extra £500 pounds per year tax relief
Then the scraped the working tax credits and made them tax credits and child tax credits and scraped the working mans tax releif or £500 per year.
Your wages are made up to a nationla minum for the amount of epole in your hosuehold.
So if you earn £6500 a year you will of course not pay any income tax, onyl NI contributions, and you will have your tax credits and child tax credit topped up to the maximum
try telling someone working part time with child care that they should just get tax releif - I don't think they will agree with your simplist view op