If you are not building a ship in your shipyard, there are no expenses for shipbuilding. Once you start building ships, the cost of that military production is now added to your overall economy. This will drag down your economy.

I suspect what was happening is that you were not building any ships, then started building ships in all of your shipyards--this can cause a big swing from surplus to deficit.

If you want to keep a surplus when your shipyards are busy, you will need to bring in more tax money (more population, or build more trade center type of buildings, or just increase tax rates) or engage in more trade with other civs. Although you may think your economy is going strong, you can do much better I think.

I can easily keep a surplus with shipyards churning out ships on my key colonies (I build shipyards on PQ >10 planets). My taxes are at 49% with 90-100% morale generally.

Usually i try to have 3-4 shipyards that can pop out a capital ship every 4-7 turns. However with tax rates i canr arley get above 39-42% without my approval going low. I try to emphasize on approval building but it doesnt make a significant difference.

I think essential ill just have to emphasise economy, a strong economy is a strong millatary.

It really is worth setting up trade routes. Design the fastest freighters you can and have one rich planet keep producing them until you have all the routes you can. A nifty trick is to have a few spare freighters positioned near rich alien planets so that if you lose a route, you can establish another one straight away. (Also you can keep an eye on those planets). Trade is usually equal to more than my surplus income.

Don't start a war unless you have 20K or so in hand is my advice. That's a minumum.

I play a gigantic galaxy and right now after taking over four other civs, i have maybe a dozen to twenty planets that pump out ships. That sounds like a lot but i also have over 100 colonies.

I keep the tax rates as high as i can without going below 65% morale and will have multiple trade only planets to keep the money flowing in.

Let the minor civs be. They usually do a lot of trade and you can park some economy starbases right outside of them.

Consistantly build ships. If you balance your economy while you are doing shipbuilding (for defence, future wars, trade whatever) then there is less of a hit when you ramp it up.

Also, if you have allies, trade for some of their warships. Even if they aren't top notch, you've at least got more defenders, freeing up your own ships to head to the front lines. Or even better, if you are on decent terms with the civ you're about to blow out of space, trade for *their* ships. In my current game i passed off Advanced Trade, Alliances and Advanced Life Support for a full 1/3 of the Torian's warships, then turned the guns around and started beating them up on the next turn.

However with tax rates i canr arley get above 39-42% without my approval going low. I try to emphasize on approval building but it doesnt make a significant difference.

Hmmm. Sounds like your populations are too high. A couple of entertainment buildings on each planet, even the worst ones, should get you somewhere over the 60% tax range. If you throw in a morale resource, a bit of morale research and a morale trade good or two, you should easily be able to support 80% tax rate with 1 basic farm on each planet.

It sounds like what you've done is let your population grow high and *then* try to up the tax rate. The better way round is to get the tax rate up to 80% (or whatever you're happy with it being long term in the game) and then let your population grow naturally as morale research/resources/trade goods kick in.

To salvage any current games, set the tax rate very high. That will kill population off until either the approval settles back down again, or you can get a reasonable tax rate without approval issues. Depends on your economic setup and exactly what sort of populations we're talking about, but the likelihood is you'll make more from a lower population with higher tax rate.

Edit: Sorry, I misread that as approvals of 39-42%. Other than in the early game when you might be after the growth bonuses, you really don't need high morale. 50-60% is usually plenty. That's the sort of number I was talking about getting with 2 entertainment buildings. Even 40% (where population will stop growing) is not an issue unless you have a voting form of government.