If you can find a nanny at £9 gross an hour:
£9 x 10 hours x 4 days = £360 Gross per week, £18,771 per year
Employers NI = £1559 per year (this figure will change as Employers NI rates change in April following The Budget) MrAnchovy's PAYE Calculator is what I used to get this figure for 2012/13 taxyear.
Weekly Expenses Kitty (for activities/outings): £5 per day perhaps. The more Based on a 48 week working year, nanny working 4 days per week, £5 x 48 weeks x 4 days= £960 total.
Nannies Travelling Costs Whilst On Duty: If your nanny uses their own car, then employers would usually reimburse the cost at £0.45 per mile (this is known as the Approved Mileage Rate). How many miles your nanny would do will vary. Consider the usual mileage they would do to take children to toddler group, other outings. I would say that I do an average of 3000 miles a year (nannying 4 days per week in a semi-rural location). Start recording the mileage you do in your car during the week, you may be quite surprised how quickly the mileage adds up even if you are just going to the local shops, library, playground, woods, PYO farm etc.
For a 4 day per week nanny I suggest factoring in at least 100 miles a week? so £45 per week, £2160 per year (48 weeks).
While your nanny is on duty, you give them food and drink. Nannies don?t really get a lunch hour, can?t leave your children home alone. So food is seen as a sort of perk in compensation for working without a break. How much does that add to your weekly food budget? I'm not sure. Nanny will eat with the children, so eat the same thing. If nanny wants something different, I feel nanny should be buying that themselves. So increase in food bill, extra £3 a day maybe? Heating/Light will also be used more as nanny is around during some of the day, so another few pounds. If comparing with a childminder/nursery, lights wouldn't be on at your home, heating may also be set low. If comparing with you staying at home, then there won?t really be much of a difference at all. There is also some additional wear and tear on the property. Shall we lump all these types of cost together? say £8 per working day. Suppose you could include cost of Employers Insurance in that (it is usually part of your home contents cover, check your policy). So 4 days x £8 = £32. 48 weeks x £32 = £1536
Payroll Admin: Use a payroll company, typical cost £135 per year.
So your costs:
Salary: £18,771
Employers NI: £1559
Payroll Admin: £135
Those are costs which tax credits will take into account, so total for those: £20465
Kitty: £960
Mileage: £2160
Food/Heat/Light: £1536
Add in those, gives you £25121
Max tax credits claim (see WTC5) with 2 children is 70% of £300, so £210 a week.
Your average weekly childcare cost for tax credits purposes is £20465/52 = £393.56
That is above the max claim £300, so assuming you get 70%, then you get £210 a week in childcare tax credit towards the cost, so £10920 a year.
So total cost: £25121, you may get £10920, leaving you £14201 to pay yourself from your take home pay. You will need to budget more to this, as things do change, so costs can go up.