Check out TurboTaxCameaF's answer below for how to verify if your Installment payment agreement has been accepted.

https://ttlc.intuit.com/replies/6782732

Edited 4/2/18 5:56 a.m.

Thank you for answering! I'm not sure if I filed Form 9465 or not... I simply selected the installment payment option when TurboTax asked how I wanted to pay. But I did get an email saying my electronic return was accepted. Does this mean I can assume the installment agreement request was also accepted, and I don't need to do anything else?

No, if you selected the installment payment plan and your e-filed return was accepted, then your installment request was received timely. You will receive a letter from the IRS confirming the agreement; however, rest assured, you submitted a timely request, so you can wait for their reply or contact them at the phone number provided above to confirm.

Great, thank you! I feel much better now. 🙂

You're welcome.