What is one of the primary functions of the Internal Revenue Service (IRS)?

The primary function of the Internal Revenue Service (IRS) is to enforce tax laws. This includes ensuring that individuals and businesses comply with federal tax regulations, accurately report their income, and pay the taxes they owe. The IRS carries out this function through various means, including audits, investigations, and the issuance of penalties for non-compliance. By enforcing tax laws, the IRS helps to maintain the integrity of the federal taxation system and ensures that government revenue is collected efficiently.

While the other options mention tasks that may seem related, they do not reflect the core mission of the IRS. For instance, the collection of state taxes falls outside the purview of the IRS as this is typically managed by state tax authorities. Providing tax advice, while a function that the IRS might offer through resources like publications and guidance, is not its primary role and is generally best handled by tax professionals. Additionally, regulating taxable investments is not within the IRS's main responsibilities; this task is more closely aligned with the Securities and Exchange Commission (SEC) and financial regulators. The enforcement of tax laws remains the most critical and direct responsibility of the IRS, ensuring compliance and proper tax administration across the nation.