The government has decided to raise taxes again. So there it is!
"there it is" refers to the facts of the current situation. It means that the taxes are already raised and it is now that it is being conveyed to the citizens. If you are probably listening this on news, then this would be followed by some sarcastic comment (most of the time it is!).
The government has decided to raise taxes again. So there is that!
"there is that" means the sentence you said prior to this idiom is apparently true. Once again, if you are listening this on news, then this may be followed by some sarcastic comment (most of the time it is!). "There is that" is often shortened to be said as "There's that".
For more reference: there it is, there is that.