Is it because of spouse income, self employment income?

There’s a calculator on the IRS website than can help.

I suggest lowering your exemptions to 0 and file single.

Another item that most people don’t know is you have have the tax table adjust your taxes as-you-go so are you get closer to year end, it will adjust your tax with holding balance accordingly.

May have to talk to HR / payroll dept to see if this is an option for you.

There are also free tax calculators at paycheckcity.com you can use to estimate.

Most people just have an additional flat amount withheld each pay period.