@kcampion - the penalties stop on the day you make the payment; not the day the return is processed.
you can make a payment today if you'd like at the IRS website. That stops the penalties and interest.
https://directpay.irs.gov/directpay/payment?execution=e1s1
Or if you mail the payment with the amended return, the IRS will pluck the check out of the envelope when the amendment is received, even though the processing of the amendment may take awhile
The IRS is not as far backlogged currently as they were in June, but I'd still assume the amendment will take 4-6 months to process.
