DDF, the way it works is this:
From 05/04/08-today (257 days)
You were entitled to:
Basic £1800
Couple Element 1770
30 Hour Element 735
CTC Family Element £545
Child Element 2085*3 (6255)
Total: £11105
Total for period 11105/365*257 =£7819.14
From today, your DH is no longer working, until 5/04/09 (108 days)
Basic £1800
Couple Element 1770
CTC Family Element £545
Child Element 2085*3 (6255)
Total: 10370
Total for period 10370/365*108 =3068.38
Total for year:
7819.14+3068.38 = £10887.52
BUT, they deduct 39% of any income between £6240 and £50000, which means that if you earn £50000 in the year, you get 39% of £43760 deducted, which is £17066.
Obviously, that leave nothing in Tax Credits.
So although they pro-rata the amounts due according to the date your circumstances change, the actual award is calculated annually.
Next year of course, if your DH hasn't found a job, you will be entitled to £10370 in tax credits, so £199.42 per week, in addition to the £60.50 per week JSA, because the JSA only totals £3146 per year, which is less than the lowest threshold for tax credits.
You will also be entitled to free school meals for your children that are in school, and healthy start vouchers for your youngest until she turns 4, and HB & CTB also.