Did you have more than one job at the same time ? Did you have more than one job all year? Are you married and you both work ?
How to Estimate Federal Withholding
Turbo tax also has a W 4 Calculator that you can use to calculate the withholding. You should update your withholding every time there is a major life event or you get a new/second job or get a substantial raise. You can use the link below to calculate your withholding.
To be clear, the amount of tax that is withheld from your pay is determined by the W-4 form that you fill out and give to your employer. If too little tax is being withheld, it's because you did not fill out the W-4 correctly. You have to give your employer a new W-4 that you adjust to have more tax withheld. You can use the Tax Withholding Estimator on the IRS web site to figure out what to put on your W-4 form. It will show you how to adjust your withholding to get the approximate refund amount that you want.