In the self-employed retirement section, TurboTax is telling you the maximum permissible SEP contribution. TurboTax will separately tell you in the Roth IRA contribution section if you have entered an excess Roth IRA contribution. Nowhere does TurboTax explicitly tell you a combined maximum. However, your combined contributions to a traditional SEP-IRA and a Roth IRA are not permitted to exceed net earnings. Net earnings are net profit minus the deductible portion of self-employment taxes. If this is a limiting factor, you might want to adjust the split of your contributions between these two accounts. Your permissible Roth IRA contribution could also be limited based on your modified AGI for the purpose and your filing status.
I don't think that TurboTax anywhere tells you the maximum that you can contribute to a Roth IRA, it only tells you if the Roth IRA contribution that you have entered exceeds the maximum. Where TurboTax is actually identifying an amount as a maximum contribution I think that this must be in the self-employed retirement section.
