You refer to "they." Was this tax return for a married couple filing jointly, or are you using "they" as a gender-neutral pronoun for one person?
The age requirements for EIC were modified for 2021 only. Could the IRS have mistakenly overlooked the special age requirements for 2021? What were the taxpayers' ages as of December 31, 2021? For 2021, to qualify for EIC without a qualifying child the taxpayer only had to be 19 or older. There was no maximum age for 2021.
