The following information is usually required during the loan process:

Copy of driver's licenses for all parties
Copy of the last 30 days of paycheck stubs
Copy of W-2 forms for 2 years prior to the current year
Copy of all pages of tax returns for 2 years prior to the current year
Copy of last 2 months' bank statements (all pages)
Copy of current home loan monthly statement (refinance only)
Contact of your home owner's insurance agent (refinance only)