They want good financial evidence of income, IRS returns are excellent evidence of what income was for prior Year, you can use IRS transcripts, in place of the returns. (1040 is a return the W-2 is a form provided by employer that has the numbers used on the 1040, the 1040 needs the W-2 to prove the numbers on the 1040(Return).
The directions included with the I-134 are quite old, and USCIS has not bothered updateing them because USCIS has no use for the form, only the consulates use the I-134.
The consulates tend to treat the I-134 like a mini-I-864 as so prefer the same financial evidence as the I-864.
In our case this what the I-134 included.
- I-134 signed and notarized.
- SIMPLE Tax transcripts from the IRS for past 3 years, (Redundant for the (1040,W2,1099) but are free from the IRS http://www.irs.gov/faqs/faq1-6.html
- Photo copy of IRS form 1040, and W2s for past 3 years (Not necessary if you provide the transcripts)
- Letter from my employer stating annual salary, job responsibility, and that is full time, on company letterhead.
- Photo copies of past month or so of pay stubs up to a few weeks before the interview.
My income was well above the povertyline so I did not include any asset data (LIKE BANK STATEMENTS or property values).
Also consider this you WILL have to provide the IRS return data later for the I-864 used for adjustment of status.