No Form 8606 is to be included with your 2018 tax return if you did nothing that would change your basis in nondeductible traditional IRA contributions, made no Roth conversions and made no nonqualified Roth IRA distribution. Your 2017 Form 8606 is still current with respect to your basis in nondeductible traditional IRA contributions; be sure to save it for future reference.
TurboTax carries your basis information on its IRA Information Worksheet. TurboTax transfers this in when you transfer in you previous year's tax return to begin your current year's tax return.
