More Tax Benefit Model Table Fun

I know I've covered this one before, but it's always good to remind ourselves of the true horrors embedded in the UK welfare system. You can check my numbers yourself by downloading the tables from the DWP website.

1. From the tables: A single unemployed parent (assume mother) with two children has net income after housing costs of £204, plus rent paid of up to (?) £209 per week.

2. From the tables: A single adult (assume bloke) earning an OK-but-not spectacular wage of £400 per week living in social housing has a net income after housing costs of £172 per week, having paid £141 rent and council tax.

3. Let's skip the whole eyes-meeting-in-the-stairwell, wedding photos and honeymoon bit, and assume that he has moved in with his new Mrs.

4. From the tables: A couple with two children, with one parent earning £400 per week has a net income after housing costs of £316. So, even though they are now using up one unit of social housing and not two, and being responsible citizens etc, they are £60 a week worse off.

Does anybody in their right mind think that this couple would not at least be tempted to do the economically rational thing, and:

a) For the two to cohabit unofficially, boosting their net income after housing costs to £517 (= her welfare income of £204 plus his wages of £315 after PAYE), i.e. by £200 per week, by £10,000 per year, or,

b) If the husband used to occupy a council flat which he can sublet for more than £141 a week, for them to cohabit unofficially and to trouser any profit they make on the sub-letting?

Answers on a postcard.