Your nanny tax obligations vary depending on the type of tax:
Income tax. You’re not required to withhold federal income taxes (or, usually, state income taxes) from a household employee’s pay, unless the employee asks you to and you agree. In that case, you’ll need to have the employee complete Form W-4 and you’ll need to withhold income taxes on both cash and noncash wages (other than certain meals and lodging).
FICA taxes. You must withhold and pay FICA taxes (Social Security and Medicare) if your household employee’s cash wages reach a specified threshold ($2,300 for 2021). If you meet the threshold, you must pay the employer’s share of Social Security taxes (6.2%) and Medicare taxes (1.45%) on the employee’s cash wages (but not on meals, lodging or other noncash wages). In addition, you’re responsible for withholding the employee’s share of these taxes (also 6.2% and 1.45%, respectively), although you may opt to pay the employee’s share rather than withholding it.
Note: There’s no FICA tax liability for wages you pay to certain family members or to household employees under the age of 18 if working for you isn’t their principal occupation. A student who babysits on the side would be one example.
Unemployment taxes. You must pay federal unemployment tax (FUTA) if you pay total cash wages to household employees (other than certain family members) of $1,000 or more in any quarter in the current or preceding calendar year. The tax applies to the first $7,000 of an employee’s cash wages at a 6% rate, although credits reduce that rate to 0.6% in most cases.