Identity
- Photo ID, and Social Security or ITIN numbers for yourself, your spouse and every dependant
- Last year’s filed return — useful context, and often required for comparison
- Bank account and routing number for direct deposit, in your own name
Income
- W-2s from every employer
- 1099s of all kinds: NEC and K for self-employment and platform work, INT and DIV for interest and dividends, B for investment sales, R for retirement distributions, G for unemployment or state refunds, SSA for Social Security
- Rental income and expense records
- K-1s from partnerships, S corporations or trusts
- Records of income that never generated a form — cash work, small side income
Deductions and credits
- Mortgage interest (1098) and property tax records
- Charitable contribution receipts
- Medical expenses, if they are likely to be substantial
- Education: 1098-T, and student loan interest on 1098-E
- Childcare provider details including their tax ID
- Retirement contributions, and HSA activity on 1099-SA and 5498-SA
- Health coverage forms: 1095-A in particular if you bought through Covered California
- Self-employed: business expenses, mileage log, home-office measurements, estimated payments already made
On sharing documents: these papers contain everything needed to steal your identity. Use a secure portal if one is offered, ask how long they retain your files, and do not email your Social Security number as a plain attachment.