I think it's because the 1099-INT must reflect the TIN owner's name, and
her name is not on his TIN (does that make sense?)
I don't know of any regulation, but if you research almost any CRM/CIF system,
they can only tax-select one party. I never saw a system that would generate
a 1099-INT with two names on it. And maybe somewhere on your signature card
he agreed to be the tax select party.
I would just ask him a few questions:
1. Does he file jointly with his wife?
If yes, then ask him what his problem is, it doesn't make a difference to IRS.
2.If no, then why doesn't he close that account and put it in his wife's name first, then his.
She can be the Tax-select party.
or:
3.How about splitting the account and opening two individual accounts (then
he can have 2 1099ints (yippee, more paperwork).
Good luck!
_________________________
Get your facts first, then you can distort them as you please. - Mark Twain