Once your original return has been accepted, you cannot change your direct debit in TurboTax.
An amended return is processed separate from your original return. The IRS will deduct the amount from your original return. You can either let them take out the money & then when they process your amended return, the IRS would send you a check for the overpayment.
Or, you can cancel the original direct debit, then just pay the amount that your Amended return shows.
Call IRS e-file Payment Services 24/7 at 1-888-353-4537 to inquire about or cancel your payment, but please wait 7 to 10 days after your return was accepted before calling. Cancellation requests must be received no later than 11:59 p.m. ET two business days prior to the scheduled payment date.
You can send in the payment in the amount stated by your amended return with a payment voucher (1040-V) or you can pay the amount in the IRS website. See the following
https://www.irs.gov/payments
1040V payment voucher:
https://www.irs.gov/pub/irs-pdf/f1040v.pdf
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For your State, you would have to check your State's website to see if you can change the payment amount and enter a new payment.
