other rules under Reg 1.469-9(d)
a) more than 50% of their personal services during the tax year are performed in real property trades and businesses in which they materially participate and
b) they spend more than 750 hours of service during the year in real property trades or businesses in which they materially participate
real property trades or businesses include development, redevelopment, construction, reconstruction, acquisition, conversion, rental, operation, management, leasing or brokerage trade or business ( IRC 469(c)(7)(C)
keeping contemporaneous records is crucial should a taxpayer be challenged by the IRS.
as @M-MTax pointed out, if you are performing these services as an employee, you must be at least a 5% owner of the employer
