Being compliant with all state and federal labor laws is complex and more than volunteers here can cover. Some links are here.
http://www.liveinnanny.org/salary-and-benefits/
https://www.nannycounsel.com/blog/why-your-live-in-nanny-shouldnt-pay-for-room-board
https://turbotax.intuit.com/tax-tips/self-employment-taxes/tax-tips-for-nannies-and-at-home-care-giv...
https://www.irs.gov/publications/p926
Here is a Florida fact sheet on live-in domestic labor
https://www.dol.gov/agencies/whd/fact-sheets/79b-flsa-live-in-domestic-workers
Here are some key points.
First, if you hire someone to work in your home, they are your employee. You must withhold social security tax from their wages and pay the IRS "nanny tax." That is essentially 7.65% of their wages that you withhold, plus 7.65% that comes from you. You may also have to pay unemployment insurance. You issue them a W-2 at the end of the year. You are not required to withhold federal and state income tax unless they ask, but if they do ask, you must withhold those taxes and remit them to the IRS on a quarterly basis along with filing form 941. You need to get a federal employer EIN to withhold taxes and issue the W-2.
Generally, anything you provide as compensation for services counts as wages, including free room and board, at the fair market rate (the rent that you could charge a stranger non-employee to live in your home, considering the room, bathroom access, kitchen privileges, furnishings, and so on.). The value of the room and board is included in their W-2 income and is subject to social security and income tax withholding.
That's your tax obligations. Everything else you need to know is about federal and state labor laws, minimum wage, and so on, and we are not experts on that.
As far as minimum wage and other state and federal employment laws are concerned, you must follow all laws and regulations, and you can be fined for not following the law. For example, the minimum wage in Florida is $12 per hour. Suppose the nanny is "on duty" from 8am to 6 pm Monday to Friday. That's 50 hours per week, so 10 hours of overtime must be included. That makes their minimum wage $660 per week. If they are on duty for an extra "date night", that's more overtime. Suppose the fair market rent on their room and board would be $600 per month or $150 per week. You could pay them a gross cash amount of $510, and issue a pay stub with tax deductions and withholding based on a wage of $660.
You may be required to follow other laws and regulations. For example, in New York, there is a "fair paycheck" law that says that employers must provide workers with a pay stub that shows certain required information, and failure to provide a conforming pay stub gets you a fine of $50 per pay check that is out of compliance. There may be laws on overtime, minimum time off, vacation, sick leave, and other benefits. You are responsible for following all the laws that apply to your situation, and I don't think any of the experts here can help with that part of the law.
