Posting again ´cus I found this memo from DHS, you can even print and take with you to the consulate if they require more than the last year tax return.
http://travel.state.gov/visa/laws/telegram...grams_2863.html"Effective immediately, sponsors filing an I-864
are required to submit only their Federal tax return for their
most recent tax year, current as of the date of execution of the
I-864. "
However, also from the same memo: "Effective immediately, income as of the time the
Form I-864 was signed should be considered on the basis of the
poverty guidelines that were in effect when the Form I-864 was
submitted in support of an immigrant visa application. The
sponsor is required to submit with their I-864 an IRS transcript
or photocopy of only the most recent Federal income tax return.
However, the sponsor may, at his or her option, submit Federal
income tax returns for the three most recent years if the
sponsor believes these additional tax returns may help establish
the sponsor's ability to maintain his or her household income at
the applicable threshold set forth in the poverty guidelines.
Note that the sponsor, by signing the Form I-864 under penalty
of perjury, certifies that the transcript or photocopy is true
and correct. This certification meets the statutory requirement
of presenting a "certified" copy and, per 28 U.S.C. 1746, the
requirement that the affidavit of support be sworn or affirmed
before a notary, consular officer, or immigration officer."