What minimum gross income threshold does Mary need to consider when deciding to file?

The minimum gross income threshold that Mary needs to consider when deciding to file is based on several factors, including her filing status, age, and the type of income she receives. For individual taxpayers under the age of 65 who file as single, the threshold for tax year 2023 is indeed $12,200. If her gross income exceeds this amount, she is generally required to file a tax return. This threshold is designed to determine whether an individual has sufficient income to necessitate filing, as those below this amount often are not required to file yet may still choose to do so to claim refundable tax credits or a refund of withholdings.

It's important to note that other thresholds may apply depending on a taxpayer's situation, such as different amounts for married couples filing jointly or if the taxpayer is 65 or older. However, in the specific context of the question, the amount of $12,200 is the correct benchmark for a single filer under 65.