You would need to amend the 2016 tax return to add the dental expenses as an itemized medical deduction on Schedule A. However, only your total medical expenses that are greater than 7.5% of your Adjusted Gross Income (AGI) can be deducted. Your total itemized deductions reported on Form 1040 Schedule A must be greater than the standard deduction for your filing status to have any tax benefit.
Standard deductions for 2016
- Single - $6,300 add $1,550 if age 65 or older
Married Filing Separately - $6,300 add $1,250 if age 65 or older
Married Filing Jointly - $12,600 add $1,250 for each spouse age 65 or older
Head of Household - $9,300 add $1,550 if age 65 or older
See this TurboTax support FAQ for amending a 2016 tax return originally completed and filed using TurboTax - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-a-return-in-turbotax/01/26768
