The IRS defines legal blindness as being unable to see better than 20/200 in your better eye even with corrective eyeglasses or contacts, or having a field of vision less than 20 degrees. The statement must be certified by a registered optometrist or eye doctor, and must accompany your tax filing. The state of blindness must be established on or before the last calendar day in a year.
Designation as legally blind must be made on IRS tax form 1040 on line 39a or 1040A on line 23a. Blind filers may not use form 1040EZ to obtain a higher deduction. The deduction amount will be subtracted from the filer's annual gross income (AGI), which will reduce the amount of money on which taxes must be paid. Blind filers who are over the age of 65 or who are married to someone who is blind and/or over the age of 65 are entitled to additional deductions.
The amount of the deduction for blindness varies from year to year. In 2009, tax filers should combine the number of factors that affect them: personal blindness, personal age (over 65), spouse's blindness and spouse's age (over 65), and multiply this number by $1,400 if single or head of household or by $1,100 if married. This value should then be added to either the itemized deduction or standard deduction amount for that year.