尊敬的8老師，
1.您在上次回答我問題裏說讓我的bother提交I-864 as the joint sponsor,（因為我父親是公民擔保人，但他沒有收入） 除了這個表還有我兄弟的身份
證明文件以外， 還需要提供他的稅單（如果需要，要提供幾年的？），工作證明，asset嗎？
-He needs to provide the copy of the most recent tax return and W2, i.e. the tax return and W2 of 2017, and also had better provide those of 2015 and 2016 (optional). He also needs to provide the employment verification letter from his employer, not need assets if his income is enough.
2.我的brother準備的這些材料是在下麵哪一步提交呢（截取移民局的來信）？-NVC will contact your father for these documents, and then your father needs to provide one I-864 though he has no income, and your brother provide another one together.
step 3: submit visa application form
step 4: collect financial dicuments
step 5: collect supporting documents
step 6: submit documents to NVC
非常感謝您！
