IRS Publication 925 page 4 at https://www.irs.gov/pub/irs-pdf/p925.pdf defines active participation.
Active participation.
Active participation isn’t the same as material participation (defined later). Active participation is a less stringent standard than material participation. For example, you may be treated as actively participating if you make management decisions in a significant and bona fide sense. Management decisions that count as active participation include approving new tenants, deciding on rental terms, approving expenditures, and similar decisions.