I underpaid last year federal taxes withholdings on W2 wages, how can i change the rate of withholding for this year?

Hi there, @thuytao. I'm here to provide several options for sorting your underpaid federal taxes. 

You need to consider various factors influencing your tax withholding for this year. The option to change the withholding rate is based on several factors, including:

•  Marital status
•  Number of dependents
•  How much they're paid
•  How often they're paid
•  Other sources of income

If you have enabled auto pay and file, please contact us to request a correction. Our team will assist you in rectifying the issue and filing a W-2c form with the SSA (Social Security Administration). You will receive a copy of the W-2c to provide to your employee and an updated W-3 copy for your records. The expert you speak with will estimate the timeline for receiving the W-2c and W-3c forms.

On the other hand, if you have auto pay and file turned off and find the mistake after filing your W-2s and W-3, you need to manually create and file a W-2c and W-3 form with the Social Security Administration.

To do this, see the General Instructions for Forms W-2c and W-3c section in General Instructions for Forms W-2 and W-3.

See this article for more details: Fix an incorrect W-2 and W-3

In addition, I've got this helpful resource to guide you on how your payroll taxes are calculated.

For the complete list of available payroll reports and how to pull them up, kindly refer to this article: Run payroll reports.

Let me know if you have any clarifications about payroll taxes. I'll be with you to assist you further. Take care, and have a good one!