請教8老師 I-864 how to split income?

8老師,

My friend is my joint/co-sponsor and filling I-864 for me now. He and his spouse filed 2019 tax return as “Married filling jointly.” Since the tax was filed “jointly,” it is hard to tell how much the part of his income is, based on the IRS Transcrip.  

Since he needs to fill out his own income on 864 form, not the income combining his spouse's, unless his spouse must file -864A. But it is not a good idea to bother another person to do this for me since my friend's own income alone is far beyond 250% federal poverty guide, not necessary to get his spouse involved. But how to deal with the “joint” income on IRS transcript to meet individual's income qualification on USCIS 864 form? Thanks.