Treasury below zero

[caravel]

You cannot build/train what you cannot afford. Going into the red (negative) is caused by support costs. The only way to offest this is to disband mercs as you have, disband any other units that you don't need, tweak the tax rate, sack some governors and appoint some better ones (for governors you need those with the best acumen stats) and if you're trading, ensure your trade routes aren't broken. Shipping can also be very costly as the further away a ship is from a friendly port the more it costs to support. So if you have a fleet just sitting there several regions away, bring it back closer to home.

Focus on very high taxes and the best governors in the key high income provinces, for example - Sweden, Flanders, Antioch, Egypt, etc. You don't need a 5 acumen governor in e.g. the Sinai or Finland. You need to be watchful of your governers as well as they may gain vices that decrease their acumen or negatively affect income or the happiness of the province. In such cases - strip their title using an emissary and give it to someone else.

[Gilrandir]

Thanks, Asai, but most of what you have written I figured out both playing myself and reading the manual. Probably I wasn't explicit in my question, so I'll rephrase it: Why having similar financial troubles (earning less than spending) you are sometimes told that you can't afford it, and other times you go into negative balance without being told anything? And how long can the negative balance situation may last before you get some palpable trouble? Perhaps it is one more bug?

[drone]

I think it is a function of how the game spends your money in the end turn phase. I believe the game first tries to purchase units and buildings on the queues first, then subtracts upkeep, then adds income. If you don't have the cash up front when you hit end turn to purchase something on one of your queues, you get the "can't afford" scroll. After purchase costs are subtracted, the unit upkeep is taken out, then the income from trade/farms/cathedrals/looting/ransom is added in. You can't go negative on buildings/recruitment, only with upkeep costs.

[Gilrandir]

You can't go negative on buildings/recruitment, only with upkeep costs.

That is true, but how long the accumulation of "negative income" may go on if you don't cut the upkeep costs? And when it drops to, say, -1000/-2000/-3000 ... florins, will it result in anything unpleasant?

[cogre]

i have been negitive 500,000 whilst fighting a war. loyalty drops like a rock in the outlying territories, thus increasing the chance for civil war ,rebellions, or dead faction reappearing.

edit- although to be fair, this might also be a result of my shipping lanes being disrupted as well as a negitive balance.

[caravel]

I'm not sure that a negative treasury has any effect on provincial happiness. A huge treasury does bring about all kinds of "irregular accounting" and corruption vices though, if my memory serves me correctly.