Final answer:
A dependent must file a tax return if their earned income exceeds their standard deduction or if they have over $1,100 in unearned income plus their standard deduction. Both types of income combined must exceed $1,100 or their earned income plus $350, minus any additional standard deduction.
Step-by-step explanation:
An individual who can be claimed as a dependent on another person's tax return must file a return if he or she has earned income and gross income that is more than the total standard deduction (including any additional standard deduction) the individual is allowed for the year. Unearned income and gross income of more than $1,100 (as per the 2020 thresholds) plus any additional standard deduction the individual is allowed for the year. Both earned and unearned income and gross income of more than the larger of $1,100 or the sum of earned income plus $350 (but limited to the applicable basic standard deduction) minus any additional standard deduction the individual is allowed for the year.
The rules for when a dependent must file a tax return depend on the type of income they receive, whether earned or unearned, and how it compares to standard deductions. These requirements are part of the broader taxation system in the United States, which uses a progressive tax rate structure as detailed in the 2020 tax rates. Understanding these rules is essential for compliance with tax regulations and accurately determining one's tax liability.