What implication should Mrs. Castro be aware of if she does not enroll in a Medicare prescription drug plan?

Choosing to not enroll in a Medicare prescription drug plan can lead to important consequences, particularly regarding premiums. If Mrs. Castro decides to forgo enrollment and later attempts to sign up for the plan, she may face higher premiums due to a penalty for late enrollment. This penalty applies if she does not have creditable prescription drug coverage—a coverage that is at least as good as Medicare's standard coverage—during that time.

The intent behind this rule is to encourage timely enrollment, ensuring that beneficiaries have access to necessary prescriptions without incurring additional costs later. Therefore, being aware of this implication encourages beneficiaries like Mrs. Castro to consider their options carefully during the enrollment period and ensures they have continuous coverage to avoid potential penalties in the future.