Here's a FAQ from the IRS website:
"FAQ: I requested a direct deposit refund. Why are you mailing it to me as a paper check?
"There are three possible reasons. They are as follows:
We (IRS) can only deposit refunds electronically into accounts in your own name, your spouse's name or in a joint account.
A financial institution may reject a direct deposit.
We (IRS) can’t deposit more than three electronic refunds into a single financial account."
Source:
https://www.irs.gov/refunds/tax-season-refund-frequently-asked-questions
