Check your withholding.
Now is a good time to make sure everything is going as expected.
Pull a pay stub and check that enough is being withheld.
Compare it with where you were this time last year and adjust based on changes in your life, income, and desired results.
If you were insane, and went exempt at any time, or made a temporary tweak to provide more take-home pay, make sure you changed it back and the change is actually occurring.
If you have doubts, get a professional to look at it.
Now is the time!
Don't wait for a bad surprise!