Okay, I took a look at your save, and a few things I feel like pointing out...
1) Planetary defense forces are sort of not worth it at all unless your enemy is bringing in some serious invasion forces. Kill those eight troops and you'll cut costs by 25k. Replace with 16 regular troops at 810 each at you'll have about the same defense at the cost of just 13k upkeep. That's at least 12k saved.
2) Your combined tax income from your four smallest colonies is less than 1k. It's not worth it to tax them.
3a) Having a bunch of different mining station designs might seem sensible, since specialization is usually the best approach to things, but remember that those paying the bill for maintenance are the civilians, and the civilians in DW are freaking loaded. It doesn't matter if the luxury mining component isn't being used. It's their dime. Also, if you don't let the civilians decide to upgrade on their own, you'll be paying for the upgrade out of your own pocket. If they make the call, they pay.
3b) The happy days where the number of mining engines alone decided how fast you pulled out resources are long gone. Two does the trick just fine and three is, IMO, the most you'll ever want to put on a mining station.
3c) As a consequence of 3a and 3b, I recommend you center on one unified gas mining station design and one unified ore mining station design. Let them have all the party favors and all the cool things you can think of. One of the first things I did was to obsolete your old mining stations and replace them with my own design that has 2 (gas) mining engines, 1 lux, 1 lab of each kind, 1 long range sensor, 2 fighter bays because why not, 3-4 shields, 10 armor, and enough energy collectors to stay in style. And they're on auto retrofit too, of course.
4) A space port over each colony is wasteful. Sorry to be blunt, but it really, really is. Take those small ports away and you'll save 5k upkeep.
5) You've got research capacity overkill like mad. Your research capacity is 1200k while your potential is only 544k. I know research is fun but there's no point to paying for labs you're not using.
6) Your large space port has a long range scanner, maxos blasters and missiles, and 4 of each plant. The scanner can just as well be outsourced to the private sector, the maxos blasters and the missiles are worthless, and 1 plant can feed 25-30 construction yards, so 4 of each is a bit on the redundant side. Cut those away and you can reduce the power supply by a lot. And that allows you to reduce the energy collectors by a lot. Which in turn means much lower maintenance. Replace the crap weapons with four fighter bays. Less power. Cut down excess labs. Even less power. After I shrunk it down some, the maintenance dropped instantly to 3300 from 4800.
7) You've got a whole heck of a lot of military ships, don't you? 20 escorts, 20 frigates, and 15 destroyers. And you're not even at war with anyone aside from the pirates. The thing is, all those ships are costing you 46k in maintenance and most of them aren't even all that strong.
8) Two construction yards on a construction ship doesn't actually mean twice the speed, at least not as far as I know.
9) It's generally a lot more useful to research the commerce and governance tech lines than, well, most of the other things in High Tech. Long range scanners, the first colonization, upping crew systems to 85 size per unit, and getting med and rec facilities are good. Getting standard transport and storage is good. Getting enhanced resource exploration is good. But after getting those things sorted out, one really should consider very carefully if econ boosting techs might be in order.
10) Your leader is kind of terrible. His stats gives -20% happiness and -10% growth and they're not skills either, so he won't ever improve those. Replace him and hope for a new leader with growth and happiness as skills.
Excellant Feedback. Thanks so much for taking a look! Time to take action!