Amend NJ Return for Medical Cost

[twpiv]

For years I was not deducting any medical expenses (line 31) from my NJ return because I didn't think I met the threshold, but after seeing a forum post I think I should have been deducting my insurance premiums (about 12k).  This premium is taken out of my paycheck but doesn't reduce box 16 (state wages) on the W2.

Am I correct that this actually is deductible on the NJ return (I know it is already deducted from Federal Wage Box 1, so it's not Federally relevant), and how would I go about filing amended returns for prior years?  How many years back can I go?  I'm sure I am going to miss out on some $$ because of my ignorance, I'm looking to minimize the pain.

[BarbaraW22]

If your health insurance premiums are included in your New Jersey wages reported in Box 16 of your W-2 (i.e. you paid taxes on the health insurance premiums), then you would be able to deduct the premiums on your New Jersey Tax return. 

Generally you have up to 3 years from the original due date of your return to file an amended return. 

If you used TurboTax to prepare your original returns, please see this TurboTax Help Article for instructions on how to amend your returns.