Last year some people found themselves facing massive tax bills at the end of the year because they weren’t withholding enough from their paychecks. If that happened to you, or if your income changed significantly this year, you need to check before the end of the year to make sure that you’re on track.
There’s a calculator on the IRS website https://www.irs.gov/individuals/irs-withholding-calculator that can help you figure it out. You’ll need last year’s taxes and your most recent paystub to get the best estimate out of it, but it’s probably worth five minutes.