Taking a quick look at your nation, a couple of things stick out for me. Peace mode - Staying in peace mode for an extended period of time decreases your population happiness and thereby reduces your tax collections. Consider changing to war mode, though this potentially opens you up to attack from other nations. Trades - making trade agreements with other nations will give your nation benefits based on what resources your trading partners have. You can try to find trade agreements here. Also, I'd delete those tanks if you're not using them - they tend to have high bill payments. When you have money, look at getting some improvements to help your financial situation as well.