Age and blindness are determined as of the end of the calendar year. The increased deduction for blindness is granted regardless of age. The dollar amount of the increase is the same for both partially and totally blind taxpayers.
Partially blind taxpayers must include a letter from their doctor stating that they cannot see better than 20/200 out of their better eye even with eyeglasses or contacts, or that their field of vision is limited to 20 degrees or less. If this letter states that the taxpayer's vision will never improve, then no further letters need be sent, and only a referral to this initial letter will need to be included with future tax returns. Otherwise a new letter must be submitted each year.