What is the primary purpose of deductions below the line?

The primary purpose of deductions below the line is to reduce taxable income. These deductions come into play after calculating the adjusted gross income (AGI) and are subtracted from AGI to arrive at the taxpayer's taxable income. By lowering the taxable income, taxpayers can ultimately reduce their overall tax liability.

In the context of tax preparation, below-the-line deductions include various itemized deductions such as mortgage interest, charitable contributions, and medical expenses (if they exceed a certain threshold). This differentiates them from above-the-line deductions, which can be taken regardless of whether the taxpayer itemizes or claims a standard deduction.

The other options relate to different aspects of tax computation but do not accurately reflect the primary function of below-the-line deductions. For instance, while above-the-line deductions can indeed influence AGI, the main role of below-the-line deductions is specifically tied to reducing taxable income. The facilitation of tax credits and property valuation are also distinct processes that don’t directly correlate with the purpose of below-the-line deductions.