Since you opened a traditional IRA, you can start making deductible contributions to it as long as you are within the income limits to do so.
If you have made nondeductible contributions for prior years, but classified the IRA as a Roth in TurboTax, the proper form was not being filled out. Nondeductible contributions to traditional IRAs are supposed to be tracked on Form 8606. That form is supposed to be filled out any year you make a non-deductible contribution. At this point, you can go back and change the last three years to include this form. You have three years from the original due date, which means if you choose to do this, you will need to complete your 2018 amended return within the next few days. The other option is to lose out on any nondeductible contributions you have made before 2021. That means the entire amount will be taxable when you begin to take withdrawals from this IRA.
