Their choices about deductions are not your concern. Advertise and negotiate in gross only.
I live in Kensington and over the years have hired three nannies. I have NEVER negotiated in anything other than gross rates (weekly salary and the equivalent hourly and overtime rate.)
In our area you can find highly qualified, great care in the $15-20/hour range (those being GROSS hourly rates of course.) How high in that range you need to go will be determined by several factors, including:
- legal working status
- fluency in English
- ability to drive
- ability to use their own vehicle to transport your child (if needed)
- amount of experience
- scope of the job - do you want any light housekeeping, meal preparation, educational activity, etc...
- the total number of hours you need (the fewer the hours, the higher your rate needs to be to get to an income level that will be attractive)
etc...
If you pay more than $20/hr you can get a college educated american, with significant childcare experience. Many parents want that. You may not get with that someone who is willing to do any level of housework. If you are willing to employ someone for whom English is a second language, and/or someone with less formal education, you are more likely to find someone at a lower hourly rate and with a broader willingness to do some level of household management (grocery shopping, meal preparation, light housekeeping).