Turbotax can't help you. You have to check your records to see if the balance due was paid. Check the return for the balance due. if paid, get a copy of the payment (front and back and account statement) and send those documents with the notice to the address indicated with a letter stating the balance was paid - documents enclosed. sign and date the letter. if you have questions about which payment the IRS is referring to, you'll need to check your account transcript
https://www.irs.gov/individuals/get-transcript
TurboTax never knows how, when or even if you paid your tax due. It is your own responsibility to either mail a check or money order to the IRS or to pay the IRS via credit card or debit card, by entering that direct debit information when you file your return or by going to the IRS payment site yourself. Your only proof that you paid your tax due is your own bank or credit card record. You can also check your own online account with the IRS to see what is shown there.
https://www.irs.gov/payments/your-online-account