• Social Security Numbers (including spouse and children/dependents)
• Child Care Provider: Name, address and tax ID or SSN
• Alimony paid/Social Security Number of recipient

Employment & Income Data:

• W-2 Forms for current tax year
• Unemployment compensation (Forms 1099-G)
• Miscellaneous income including rent (Forms 1099-Misc)
• Partnership, S Corp & Trust Income (Schedules K-1)
• Pensions and Annuities (Forms 1099-R)
• Alimony received
• Jury Duty Payments
• Gambling and Lottery winnings (keep track of losses in route to winnings)
• Prizes and awards
• Scholarships and Fellowships
• State and Local income tax refunds (Form 1099-G)

Homeowner/Renter:

• Residential address(es) for this year
• Mortgage interest (Form 1098)
• Sale of home or other real estate (Form 1099-S)
• Second mortgage interest paid
• Real Estate Tax paid
• Rent paid during tax year
• Moving expenses (when moving for business related)

Financial Assets:

• Interest income statements (Form 1099-INT and 1099-OID)
• Dividend income statements (Form 1099-DIV)
• Proceeds from broker transaction/stock sales (Form 1099-B)
• Retirement plan distribution (Form 1099-R)
• Investment Schedule K-1

Sometimes your financial institution provides transactions on a consolidated form.

Financial Liabilities:

• Auto loans and leases (account numbers and car value) if used for business
• Student loan interest paid
• Early withdrawal penalties on CDs and other time deposits

Automobiles:

• Personal property tax information

Expenses:

• Gifts to charity.
• Unreimbursed expenses related to volunteer work
• Unreimbursed expenses related to your job (travel, uniforms, union dues, etc)
• Investment expenses
• Job hunting expenses
• Child Care expenses
• Medical Savings Accounts
• Adoption expenses
• Alimony paid
• Tax return preparation expenses and fees

Self-employment:

• Business Income (Forms 1099-MISC and/or own records)
• Partnership SE income (Schedule K-1)
• Business-related expenses (Receipts, other documentation or records)
• Farm related expenses (Receipts, other documentation or own records)
• Employment taxes and other business taxes paid for current year (Payment)

Miscellaneous Tax Documents:

• Federal, State and local estimated income tax paid for current year (Estimated tax vouchers, cancelled checks and other payments records)
• IRA, Keogh and other retirement plan contributions
• Records to document medical expenses
• Records to document casualty or theft losses
• Records for any other expenses that may be deductible
• Records for any other revenue or sales of property that may be taxable or reportable