Final effect is that interest rate goes down, and output is in principle ambiguous. Regarding output, if said output constant then nothing else happens. Consumption goes down because T increase. If output constant nothing else happens. If output decreases C decreases too.
Unemployment varies negatively with output.
If output constant U constant too. Short interest rates fall today and in the future, thus long term interest rates fall too. Stock prices can decline if Y suffers a substantial decline, this is so because Y affects the size of dividends. It is probably that the stock price will increase today, due to the lower future interest rates. But it could be the case that the increase in future taxes decreases future income, causing lower future dividends.