I contributed 6K of post-tax to traditional IRA. Then converted $968.92 of that traditional IRA to a Roth IRA. Turbo Tax says that I over contributed . How to fix this?

[dmertz]

Make sure that you did not separately enter a Roth IRA contribution.  You did not make a regular Roth IRA contribution, you made only a regular traditional IRA contribution.  The Roth conversion is reportable on the tax return for the year in which the Roth conversion occurred by entering the Form 1099-R that you receive reporting that conversion.