回复：对不起, 重问一下-您说凭工作申请公民要交5年的tax return transcripts

You just need the last three years of the tax return transcripts for the US citizenship application (N-400 filing).

See

http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=6f547db185e43110VgnVCM1000004718190aRCRD&vgnextchannel=11616c854523d010VgnVCM10000048f3d6a1RCRD