The downturn in the stock market may have caused the value of your retirement account to decrease. But if you have a traditional IRA, this decline may provide a valuable opportunity: It may allow you to convert your traditional IRA to a Roth IRA at a lower tax cost. Traditional vs. Roth Here’s what makes a traditional IRA different from a Roth IRA: Traditional IRA. Contributions to a traditional IRA may be deductible, depending on your modified adjusted gross income (MAGI) and whether you (or your spouse) participate in a qualified retirement plan, such as a 401(k). Funds in the account can grow tax deferred. On the downside, you generally must pay income tax on withdrawals. In addition, you’ll face a penalty if you withdraw funds before age 59½ —...