To calculate the maximum permissible SEP contribution, mark the Maximize box for a SEP contribution in the self-employed retirement section of TurboTax. After that, you can enter the maximum annual Roth IRA contribution limit of $7,000 for 2024 ($8,000 if age 50 or over in 2024) and see if TurboTax indicates any of this as being an excess contribution. If TurboTax shows an excess contribution, go back an reduce the originally entered amount by the amount TurboTax indicated as being an excess contribution.
Filing an extension is irrelevant to making the the Roth IRA contribution. The deadline to make this contribution for 2024 is tomorrow, April 15, 2025.
