Do you mean you did not receive it on your 2020 tax return ---- or that you did not receive a monthly advance payment?  Please be specific.   How old is your child?   Does your child have a Social Security number?   Did you file a 2020 tax return?

I'm not the OP but am in the same boat.

My child was born June 2021.  I did not receive a Child tax credit in the amount of $3600 though the 8812 is filled out and included with my 2021 taxes. I also did not receive the $1400 stimulus for that child. My child has a SSN which was included when I filled out online with Turbo Tax deluxe.  I have filed a 2020 return, but obviously the child was not on it at the time (not born yet).

Do I need to do an amended return? Thank you for your help!

@jaketrilla1 You need to file a 2021 tax return in order to get the child tax credit and the 3rd EIP.  Amending 2020 will not get either credit for you.

Make sure you have entered your child as a dependent in My Info, and that you have entered the child's Social Security number. If your child was born in 2021make sure you said he lived with you the whole year.  There is an oddly worded question that asks if the child paid over half their own support.  Say NO to that question.

Your 2021 child tax credit will be on line 28; your 2021 recovery rebate credit (stimulus) will be on line 30.

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

It depends. You may have gotten the credits and were not aware, you may not be eligible for them, or something was incorrectly filled out on your return making you ineligible for them. If you included a Form 8812 with your newborn's information the $3,600 credit should have been added automatically to your tax return if you were eligible. Likewise with the newborn's stimulus payment if your household was eligible. In total, that should have been an extra $5,000 added to your tax return. You can check to see if both credits are on Form 1040, Line 28 has your Child tax credit and Line 30 has the recovery rebate credit for any missing stimulus money from the third payment. 

Both credits can be reduced or eliminated due to household income. The recovery rebate credit and child tax credit starts to be reduced if your income is above:

• $150,000 if married and filing a joint return or filing as a qualifying widow or widower
• $112,500 if filing as head of household or
• $75,000 if filing as a single or as married filing separately.

If you did not receive the credits and you were eligible, then you may need to file an amended return. As for what went wrong the first time, I would check the information on your child. To be eligible for the credits, you will want to mark that the child lived with you all 12 months, even though they were born in June. Did your child pay for more than half of her living expenses?  Make sure you answer No. Also, on the screen where you enter the child's social security number, there is a box underneath that says Your child's Social Security Number is not valid for employment. Make sure it is not checked.

@jaketrilla1