Just seems like the correct building for this but, recovery of 1-2% of the 20% mining sales tax into the base directly is one way to create a shared fund without too much effort. People are always selling some minerals.

+1...this is good because i hate losing that 20%...maybe even make the tax to 5% into the base

And then we can withdraw this money to reduce our tax losses! BANG ON!
+1

+1 even if it's on top of the 20% sales tax it'd be a quick and dirty way to make sure that everyone's contributing to the base, and you can always turn around and take it back.

like the idea and will help with the upkeep

Yes, the trick was to combine a small benefit (reduced sell tax) with a contribution to base that is scaled based on the person's income (ie, "taxing" everyone's income, but yet not reducing it). Generates upkeep and base spending money passively, which works for most people.