My clients received letters they were issued $1400 each (joint return) - however they did not get the $$.

Put 0 in the worksheet for the $2800 and worksheet shows they get a credit of only $700 on the return. 2020 gross income was under 150,000 but 2021 income 157,000. Is the worksheet using the 2021 income to figure the credit? Seems they should be getting the full $2800 credit. What's up??