What could result in a user incurring IRS fines or penalties in the US?

Not reporting a Taxpayer Identification Number (TIN) can lead to significant issues with the IRS, including potential fines and penalties. In the U.S., the TIN is a critical piece of information for tax reporting and compliance. If a taxpayer fails to report their TIN, it can complicate the tax filing process, resulting in the IRS potentially viewing the tax return as incomplete. This incompleteness can trigger penalties for failure to provide critical information required for accurate tax assessment.

Additionally, beyond just fines, not reporting a TIN could lead to delays in processing tax returns, issues with refunds, or even increased scrutiny from tax authorities. The IRS expects accurate and complete submissions because it helps ensure the proper collection of taxes. When the required TIN is absent, it disrupts this process, ultimately resulting in penalties for the taxpayer involved.