Get your taxes done using TurboTax

In general, the W-4 system is supposed to be self-adjusting.  If your withholding is basically ok now, when you stop your 401k and your taxable income goes up, your withholding should automatically go up proportionally.  You shouldn't need to make a specific change for this event.  You can certainly double-check with the IRS web site once the payroll change is processed.