Taxesgal, you are completely wrong, and I am very surprised you were given two cheers.  "Resident alien" is not synonymous with "green card holder."  This is very clear in many IRS publications.  There are two ways to be a "resident alien" under IRS rules.  Only one of them has anything to do with being a green card holder.  The other one is called the substantial presence test, and makes anyone who has been in the US for a certain amount of days a "resident alien."  Here are two links out of literally hundreds I could choose from that say so very clearly.  https://www.irs.gov/individuals/international-taxpayers/determining-alien-tax-status   https://www.irs.gov/individuals/international-taxpayers/substantial-presence-test 

There are many, many types of DHS work authorization.  One is, for example, a (c)(9), which is when someone has filed for their green card but has not yet received it, since USCIS is so incompetent that it often takes them years just to make a decision on one of these applications, no matter how clear cut it is.  In that scenario, a (c)(9) work authorization is meant to allow the person to work while they wait for their green card.  That person would most definitely be entitled to the EITC, as long as they meet the substantial presence test.  So would someone with, for example, a (c)(10) (pending cancellation of removal application in immigration court) or a (c)(8) (pending asylum application).

Jul21720, yes, you would first check if their EAD card has expired.  Even if it has, there are many situations where they might have a paper called an I-797 which extends their card's validity for another 180 days if they have filed for an extension but it hasn't been approved yet.  Again, USCIS is very slow...  The rule is that the person's SSN must be valid when the tax return is filed and before the due date of the return (which this year would be April 15).  So this year, for example, if someone comes to me on March 1, 2021 to file their 2020 taxes, and their EAD will expire on April 1, 2021, they would be eligible for the EITC as long as everything is filed before the EAD expires.