[Suicide Junkie]

As far as SE4 v1.35, having no spaceport meant you got zero.
I have used this to my advantage sometimes, giving me time to build enough slave labour camps to be profitable before giving up my 1000 "charity" resources.

If you still get 25% without a spaceport in newer Versions, then you're gonna just have to slog through it using stored resources.
Try building one in a non-spaceport system, and see what happens.

If you get the 25%, then start with spaceports. Emergency Build SLCs on all of your planets, especially those in Bi- or Tri-nary starsystems (cause they get 2-3x the resource output). When they all complete on the same turn, you will have been collecting the "charity" during the build turns, and should now be making at least 1000 each resource.