Traditional to Roth IRA rollover question

[James S.]

I have a question regarding rolling a traditional IRA into a Roth. Given:

• A traditional IRA that was funded via a closed 401k and grew for several years, with a value of $15,000
• A recent after-tax contribution to that IRA of $5,5000, bringing the IRA's value to $20,500 (this contribution will not be deducted)
• I roll the traditional IRA's assets into an existing Roth

Would I now pay taxes on the $15,000 but not the $5,5000?  Would I be required to submit and retain a Form 8606 for the non-deductible $5,500?

Thank you in advance for your help!