My case is a little bit different, but I'll share my experience nonetheless! I am preparing for my interview and before I got DQ'd at the NVC we had submitted my sponsor's tax returns for the past three years, but his most recent tax return was filed as zero dollars because he lived with me in Canada for that tax year and did not work or make any income. He moved back to the US and only began working four months before we had to submit our documents to the NVC. His income was above the poverty guidline, so we did not add a joint sponsor at the time, we just submitted a written explanation of why he made no income for the most recent tax year, along with his paystubs, an offer letter, and his current lease to further prove he's domiciled in the US again. They did accept the documents and they did DQ us, but they also notified us that my sponsor did not meet the income requirements and that I should have a joint sponsor prepared for my interview where the officer will make their final decision. Even though his income was above the poverty limit, I guess the fact that he had a large gap in work/income history prompted them to recommend a joint sponsor. We did not use assets, so maybe having income plus assets will be enough, but if you can in any way find someone willing to be a joint sponsor as a backup it would be the safest option. Good luck!
