A credit check is the foundation of this process. Many home buyers choose to inspect and clear their credit reports before applying for a mortgage. W-2 forms allow the underwriter to scrutinize income and job history, which directly affect applicants' buying power and help reveal how great a risk they might be to the lender.
Pay stubs help confirm current income level and verify the applicant's employment.
Upon closing, most lenders reconfirm employment, especially if much time has passed since the loan was underwritten. Bank statements indicate the applicant's resources. Tax returns provide a wealth of financial information.