I've had one for years. Keep updating tax brackets, trying to estimate tax load. It's as good as the effort put in. Bit of a pain: this past year I was given some stocks, some of which were sold to pay taxes. But I didn't sell the stocks... and the stock sold to pay for the income tax was in the next up bracket... so it's starting to convoluted.
Each year I do a save-as and keep last years version. I can dig back into the past if I wanted. No good reason but sometimes it's nice--I can tell that I really didn't care about this stuff in pre-2013 as a result, as I don't have records.
But making a budget is different than keeping to a budget, I've found. As a rule I like to keep a healthy buffer at the end, money not allocated. Because somehow it gets spent anyhow.