Which taxpayer(s) will be required to file a 2021 federal income tax return? None of the individuals are blind.

Carl (66) has gross income of $13,750. He is single and has no dependents.

Cassidy (34) has gross income of $18,550. She will file as head of household with one dependent.

Maddie (27) and Calder (25) are married and have gross income of $24,900. They lived together all year and wish to file a joint return.

Noel (66) and Deborah (63) have gross income of $26,950. They wish to file a joint return.