Using a tax withholding estimator like the TurboTax calculator or a W-4 calculator has many benefits. It helps manage your tax withholdings to avoid paying too much or too little, preventing unexpected tax bills or underpayment penalties. It also lets you adjust your withholdings to optimize your paycheck and plan for life changes that might affect your taxes. For future planning, consider using the tax refund calculator tax filing season to estimate your upcoming tax situation.