The day used as the base date for counting anniversaries in the traditional Japanese age system (e.g. years of career, years since entering a company, grade in school, and after death) is mostly the corresponding day (e.g. the date of entering a company, the date of entering a school, and the date of person's death).
なお、記念日としての数え年（経歴、入社年数、学年等や没後など）の数え年の加算日は、その記念日の応当日（入社日、入学日、没日など）を基準とすることが多い。