In 2019, I qualified for the child tax credit but was disqualified for 2020. What makes a person qualified and disqualified? Thank you

[Critter-3]

There are 6 possible reasons; you aren’t getting the Child Tax credit (CTC). It’s usually #4:

1. You’ve entered something wrong. In the personal Info section, for the dependent, you must select answers that indicate that he/she is your dependent child. If the child was born during the year, say he/she lived with you all year (note: TurboTax changed how this section is done two years ago, you may need to go thru the interview again or even delete your dependent and start over). If the child was born in 2020, you have to answer that he lived with you all year. The CTC is not an automatic $2000, per child. It is income dependent. If you haven't entered your income yet, the CTC will not show.
2. Your child may be  too old (over 16). You can still claim your child, as a dependent. What you can't claim is the Child tax credit. This comes as a big surprise to many parents the year their child turns 17. A child over age 16 no longer qualifies for the Child Tax credit (CTC). Although a child can still be a student dependent through age 23, and a qualifying child for EIC,  the Child Tax Credit expires the year they turn 17 and you no longer get the $2000 CTC. Instead you will get the non-refundable (up to) $500 Other Dependent Credit.
3. Your income is too high. The Child Tax Credit (CTC) is phased out at higher incomes starting at $400,000 for joint filers  ($200K single). You lose $50 for each $1000 (rounding up) your income is over that threshold.   

Previously it was $75,000 for single, head of household, and qualifying widow or widower filers; and $110,000 for joint filers.

1. Your income is too low.  The child tax credit  (CTC) is also limited to your tax liability. The CTC is a non-refundable credit and can only reduce your income tax to 0, It can not help you beyond eliminating your tax liability. But, if you have more than $2500 of earned income, some or all of it is usually given back to you thru the "Additional Child tax credit". That is, part of the CTC may be on line 18b of form 1040 (2019 version) instead of line 13a (lines 17 and 12 in 2018).   The  ACTC is calculated on form 8812 and  is basically 15% of your earned income over $2500. The ACTC is a maximum of $1400 per child (not $2000).
2. You are the custodial parent and the non-custodial parent is claiming the dependent this year. The CTC goes with the dependency, even though the custodial parent still gets the Earned Income Credit, Dependent care credit and Head of Household.
3.  Another possibility is that part of your tax due is not regular income tax, but is self-employment tax (FICA), early distribution penalty or another type of additional tax, for which the CTC cannot be used.

To get a 'second opinion' on-line direct from IRS, try https://www.irs.gov/uac/is-my-child-a-qualifying-child-for-the-child-tax-credit

TT FAQ https://ttlc.intuit.com/questions/2625810-why-didn-t-i-get-the-child-tax-credit-or-why-is-it-less-th...

https://www.irs.gov/uac/Ten-Facts-about-the-Child-Tax-Credit

[runway1978]

Thank you so much. It’s probably because my income was low. I’m not sure but I’ll contact Turbo Tax for a second review. 

[Critter-3]

For 2020 only you had the option to use the 2019 earned income in a "look back" option for the EIC  and the CTC  ... look in those sections of the interview where is asks if you would like to try this function.