What are Bonus Drugs or Supplemental drugs and how are they covered by Medicare Part D?

Bonus or Supplemental drugs are medications specifically excluded from the Medicare Part D program - although they may be covered by your Medicare drug plan (as a "bonus").

Since these drugs are not covered by the Medicare Part D prescription drug program, supplemental or bonus drugs do not count toward meeting any of your Medicare Part D plan limits such as Initial Deductible or maximum out-of-pocket spending limit (RxMOOP).

Bonus or supplemental drugs may also include over-the-counter (OTC) drugs (that are also not covered by the Medicare Part D program) such as cough or cold medicine.

Bonus drugs may include, such non-Part D drugs as:

B Complex w/Vitamin C
Cyanocobalamin (B12) injections or tablets
Folic Acid
Levitra
Mephyton
Multiple Vitamin Injection
Viagra (or other ED medications)

The Centers for Medicare and Medicaid Services (CMS) defines Medicare Part D Supplementary (or Excluded) Drugs as:

"[A]ny drug for which as prescribed and dispensed or administered to an individual, payments would be available under Parts A or B of Medicare for that individual, even though a deductible may apply.

In addition, the definition of a covered Part D drug specifically excludes drugs or classes of drugs, or their medical uses, which may be excluded from coverage or otherwise restricted under Medicaid under section 1927(d)(2) of the Act, with the exception of smoking cessation agents. The drugs or classes of drugs that may currently be otherwise restricted under Medicaid include:
Agents when used for anorexia, weight loss, or weight gain (even if used for a non-cosmetic purpose (i.e., morbid obesity)).
Agents when used to promote fertility.
Agents when used for cosmetic purposes or hair growth.
Agents when used for the symptomatic relief of cough and colds.
Prescription vitamins and mineral products, except prenatal vitamins and fluoride preparations.
Nonprescription drugs.
Covered outpatient drugs which the manufacturer seeks to require as a condition of sale that associated tests or monitoring services be purchased exclusively from the manufacturer or its designee.
Agents when used for the treatment of sexual or erectile dysfunction (ED). ED drugs will meet the definition of a Part D drug when prescribed for medically-accepted indications approved by the FDA other than sexual or erectile dysfunction such as pulmonary hypertension.
However, ED drugs will not meet the definition of a Part D drug when used off-label, even when the off-label use is listed in one of the compendia found in section 1927(g)(1)(B)(i) of the Act: American Hospital Formulary Service Drug Information, and DRUGDEX® Information System. ED drugs meet the definition of a Part D drug only when used for FDA-approved indications.

While these drugs or uses are excluded from basic Part D coverage, Part D sponsors can generally include them as part of supplemental benefits, provided they otherwise meet the definition of a Part D drug. Because over-the-counter (OTC) drugs do not otherwise meet the definition of a Part D drug, they may not be included as part of supplemental benefits; however, under certain conditions as part of a plan utilization management program, OTC drugs can be provided at no cost to enrollees. The cost of these drugs to the Part D sponsor would be treated as administrative costs under such programs."

Sources include:

CMS Medicare Prescription Drug Benefit Manual, Chapter 6 – Part D Drugs and Formulary Requirements, Section 30.4 - Transition (Rev. 18, Issued: 01-15-16, Effective: 01-15-16; Implementation: 01-15-16)