Last year, with a raise and a sizable bonus due to some very long stays in a hotel working on a big project, I ended up making almost 20% more than what I had in previous years. Coupled with a dependent who is now employed and filing his own taxes, which I forgot to adjust on my W4. I ended up owing a big portion this year.
Edit:
I hate that "damn" is filtered.
Edited, Mar 13th 2015 6:39pm by TirithRR