Final answer:
A taxpayer's sister with a gross income of $4,100 likely does not qualify as a dependent under QR due to income limits, and without further information, QC status is uncertain. A family of three living on $20,000 faces challenges in meeting the poverty threshold. Tax rates for different income levels and household types are crucial to understanding overall economic well-being.
Step-by-step explanation:
Understanding Tax Requirements and Poverty Thresholds
When considering if a taxpayer's sister is a Qualifying Child (QC) or Qualifying Relative (QR), both, or neither, the IRS rules must be examined. Given her gross income exceeds the threshold for a qualifying relative, she may not be claimed as a dependent under the QR test. However, without additional details about her age, relationship, residency, and support provided by the taxpayer, it cannot be definitively concluded if she is a QC.
In the context of the official poverty threshold, a family of three earning $20,000 may struggle to make ends meet, especially since this income level may fall near or below the threshold set by the U.S. government. According to the LibreTexts™ material, a household's challenges are further compounded if the income increase is minimal compared to government benefits, as exemplified by the case where household income rises by only $400 over benefits.
Regarding taxation, if an individual's or household's earnings are modest, such as the $16,000 earned through government benefits, the issue of marginal and average tax rates becomes pertinent. The tax burden on low-income earners can significantly impact their ability to achieve a sustainable lifestyle, which is why comparing tax rates between individuals and married households can reveal disparities in tax liabilities.