Tax Credits are calculated in stages. The three stages are:
Child Tax Credits
Working Tax Credits
Child Care Tax Credits
Working out each element:
Child Tax Credits:
1 x Family element: £545
3 x Child element: (3x2720) £8160
Total: £8705
Working Tax Credits:
1 x Basic element: £1920
1 x Couples element: £1970
1 x 30 hr element: £790
Total: £4680
Child Care Tax Credits:
Child care costs: £323 per week.
£23 disregarded as over threshold.
£300 x 52 weeks =£15600
70%=10920
Total: £10920
Any deductions are first taken from the Child Care Tax credits, then Working Tax Credits, then Child Tax Credits.
You are allowed £6420 in earnings, deduction free.
£30,000 - £6420 =£23580
The remaining £23580 is reduced by 41p in every pound, from your tax credits.
£23580 x 0.41 = £9667.80
So, taking firstly your Child care Tax Credits:
£10920-£9667.80= £1252.20
This means that your total Tax Credits will be:
Child care: £1252.20 per year (£104.35 per month/£24.08 per week)
Working Tax Credits: £4680 (£390 per month/£90 per week)
Child Tax Credits: £8705 (£725.42 per month/£167.40 per week)
Total: £14637.20 per year/£1219.77 per month/£281.48 per week.
The advisor was right, I think. If you were overpaid last year, that overpayment will first come from the Child Care Tax Credits. As they say you were overpaid by £4000, then all of the Child Care Tax Credits and the first £2800 of the Working Tax Credits will be swallowed up by that.
That isn't to say that you definitely were overpaid - you need to check that out. However, on the face of it, if that is correct, then the advisor was correct 