Filed my 確定申告 in March. Just realized I forgot to claim the 医療費控除 (medical expenses deduction) for my dental work — about ¥80,000.
Is it still possible to file a 還付申告 (refund claim) after the May deadline? Or does that only apply if you didn't file at all?
Couldn't find a clear answer in English. If anyone has done this in 2026 specifically, would appreciate the guidance.