Per IRS Instructions for Form 8888 Direct Deposit of Refund to More Than One Account:
Page 2: Purpose of Form
Use Form 8888 if:
You can't have your refund deposited into more than one account or buy paper series I savings bonds if you file Form 8379, Injured Spouse Allocation.
Deposit of refund to only one account. If you want your refund deposited to only one account, don't complete this form. Instead, request direct deposit on your tax return.
Account must be in your name. Don't request a deposit of your refund to an account that isn't in your name, such as your tax return preparer’s account. Although you may owe your tax return preparer a fee for preparing your return, don't have any part of your refund deposited into the preparer's account to pay the fee.
The number of refunds that can be directly deposited to a single account or prepaid debit card is limited to three a year. After this limit is reached, paper checks will be sent instead. Learn more at www.irs.gov/Individuals/Direct-DepositLimits.
Page 3: Reasons Your Direct Deposit Request Will Be Rejected
If any of the following apply, your direct deposit will be rejected and a check will be sent instead.