@Melanie27 you would need to fill out a new W4 form.
Fill out the information in Step 1 and choose head of household.
If your dependent is a child under the age of 17 you would fill in the top line of Step 3.
If your dependent is a parent or child 17 and older you would fill in the second line in Step 3.
We have a useful tool to help estimate what your withholding should be and it will assist you on how to fill out your W4.
W4 Estimator
