Child and Dependent Care Tax Credit Enhancement Act of 2021 This bill modifies the tax credit for employment-related expenses incurred for the care of a taxpayer's dependent to (1) increase to $400,000, the adjusted gross income threshold level above which the credit is incrementally reduced; (2) increase the dollar limits on the allowable amount of the credit; (3) specify rules for married couples filing separate returns; (4) allow an inflation adjustment to the adjusted gross income threshold and the maximum credit amounts, beginning after 2022; and (5) make the credit refundable.