I just had an interesting situation come up that I took advantage of.  Single taxpayer, age 71 retired in June 2019.  Made like $12,900 in W2 wages that year in first half of year before retiring.

He gets 24,500 in Social Security benefits and drew $5,200 from IRA in 2021.  He has no earned income this year, but if you manually go into EIC worksheet and choose to use 2019 earned income, he gets $1,317 in EIC this year.

With the new EIC rules increasing the EIC for childless taxpayers and expanding it age wise to unlimited, this situation played out.  So beware and look out for taxpayers who retired in 2019 or young people who had no earned income in 2021.