2020 CA DE-4 form Worksheet C Item 13: how do I calculate it?

Hi,

 

I'm filling out the 2020 CA DE-4 form.  Item 13 of worksheet C says "Calculate the tax withheld and estimated to be withheld during 2020.".  I can look up my year-to-date withheld amount from my last paystub for the amount already withheld in 2020.  But how do I calculate the estimated amount?  

 

Thanks.