Asteroids (including dead ones) require only one upgrade to bring the underdevelopment tax rate to zero. All other planets require two Civilian Infrastructure upgrades to bring the underdevelopment tax to zero.
One correction, Ovangkol: two upgrades on non-asteroid planets is sufficient to bring the planet to positive income. The third (Ice, Desert and Terran) and fourth (Terran only) CI upgrades increase maximum population at that point.