"[1] Compensation that is 'reasonable' under other federal tax rules can still be taxed as 'excess' compensation.... [2] To know whether it might pay compensation that triggers the tax, a nonprofit ... must keep track of its 'related' entities and any compensation paid by those entities to shared employees.... [3] 'Remuneration' counts once there is no substantial risk of forfeiture.... [4] Each common-law employer, whether it is the nonprofit or a related entity, must pay its share of the tax based on its proportional share of remuneration paid to a covered employee."  MORE >>