You cannot combine this with the medical expense deduction. Calculate which is more beneficial. Eligible medicines are indicated on receipts with a “★” mark or similar. For 12,000 yen, many people can reach this amount just by stocking over-the-counter medicines. A list of medicines eligible for the self-medication tax system is posted on the Ministry of Health, Labour and Welfare website, and receipts at the time of purchase indicate eligibility. To apply the self-medication tax system, you must attach a self-medication tax system certificate summarizing eligible medicine purchases to your income tax return. Originals are not required, but receipts and documents proving the health-promoting activities must be kept for five years.