HI @InnerMogul 

Thanks for the question. You may want to fill out a new W4 once your son is born. Step 3 of the W4 has a post for you to list dependent children under age 17. This should reduce your withholdings slightly to account for the Child Tax Credit you will receive on your return from that year forward. It's not necessary that you do this, your refund may be slightly higher on Tax Day. Keep in mind that filing a new W4 could change any other selections you have made in previous W4s so you may want to ask for a copy of the old one from your payroll department. 

I hope this helps! 

Hi @johnd84 Quick Follow-Up, given that my wife will not be working (on State Disability), would I be able to adjust the deductions further? or should I only claim the 1 dependent in my son?