In general, the documentation you will need includes:

Property Information (if you already have a contract on a house)

Purchase Agreement.

If you have sold your current home, copy of settlement statement (HUD-1).

Income & Assets

Pay stubs for the last 30 days.

For the past two years:

W-2s

Statements for each bank, mutual fund, and/or investment account for the last two months.

If you own more than 25% of a business:

Corporate or partnership tax returns for the past 2 years.

If self-employed:

Tax returns for the last two years (with schedules).

If you own rental property:

Tax returns for the last two years.

If you are retired:

Pension Award Letter.

If you receive Social Security:

Social Security Award Letter.

If you are counting child support as income:

Copy of divorce settlement.

VA Loans

Copy of DD Form 214, Report of Separation.

Miscellaneous

Photo ID.

If applicable, a copy of your divorce decree.

If you are not a citizen, a copy of the front and back of your green card.