the IRS has not released any info on how to update DD a/c. your 2020 return can't be e-filed until late January 2021. the IRS will send out payments before 1/15/2021 so if you have an invalid DD a/c the deposit will be sen back and the IRS may issue a paper check. but if it can't do so timely, you'll have to claim the second stimulus when you file your 2021 return.
from the IRS
The IRS emphasizes that there is no action required by eligible individuals to receive this second payment. Some Americans may see the direct deposit payments as pending or as provisional payments in their accounts before the official payment date of January 4, 2021. The IRS reminds taxpayers that the payments are automatic, and they should not contact their financial institutions or the IRS with payment timing questions.
As with the first round of payments under the CARES Act, most recipients will receive these payments by direct deposit. For Social Security and other beneficiaries who received the first round of payments via Direct Express, they will receive this second payment the same way.
Anyone who received the first round of payments earlier this year but doesn’t receive a payment via direct deposit will generally receive a check or, in some instances, a debit card. For those in this category, the payments will conclude in January. If additional legislation is enacted to provide for an additional amount, the Economic Impact Payments that have been issued will be topped up as quickly as possible.
clarification of what this means
Jan. 15 is the cutoff date in the $900 billion stimulus bill; after the middle of January, the IRS and US Treasury must stop sending payments. If you don't receive your full second stimulus check money by Jan. 15, you will need to claim all or part of the missing amount you qualify for when you file your federal tax returns in 2021 through the Recovery Rebate Credit. You'll also be able to claim any money the IRS still owes you from the first round of payments.
