Final answer:
Option (b) is the correct answer as a taxpayer must provide a social security number, individual taxpayer identification number, or adoption taxpayer identification number to claim a qualifying relative as a dependent.
Step-by-step explanation:
The correct answer to the question "All of the following statements regarding a taxpayer's identification number are true, except?" is option (b).
A social security number, individual taxpayer identification number, or an adoption taxpayer identification number is indeed required for a taxpayer to claim a qualifying relative as a dependent on their tax return. Without one of these forms of identification, the IRS cannot process the dependent for tax benefits. This identification must be provided on the tax return for the tax year for which the taxpayer is claiming the dependent.
It is worth noting that option (d) is inaccurate as well. A taxpayer can amend a return to add a dependent whose identification number was received after the due date of the return.