All nonprofits are encouraged to be active advocates of their mission. However, the IRS allows 501(c)(3)s to engage in lobbying as long as it is not a “substantial part” of their activities. 501(c)(4) social welfare organizations and 501(c)(6) trade associations may engage in lobbying activities without limits; in fact, that can sometimes be one of their main functions. As the “substantial part” definition is rather ambiguous, public charities that lobby should understand the monetary parameters for what constitutes “substantial.”
It is important to remember that political activity — campaigning in favor or against a candidate — is strictly prohibited for a charity. A violation of the IRS regulations may result in the organization losing its tax-exempt status or having to pay excise taxes on the money improperly spent.