London will accept an employer letter saying your current yearly salary as proof of your income with nothing else. No need to provide the skimpy tax return.
Mum can do an I-34 instead of you.
He can self sponsor and you and Mum need not submit an I-134. He needs to take financial statements showing his savings to the interview. Sometimes the document collector will, out of habit, ask for the I-134, at which point he says “I am self-sponsoring” And turn over his financial proof.
London is not very demanding when it comes to the I-134. They don’t even require a tax return from the fiancé if you have another proof like employer letter. If you can’t sponsor they want the I-134 from the person with the money like Mum. Or your fiancé can present his financial assets and self-sponsor without an affidavit of support.
The rules for an I-864 when he applies for adjustment of status are different, but all of the above mentioned have worked for fiancé’s visas in London.
