Tax document checklist for 2026: build each client's list from last year's return

The documents a client needs for a 2026 federal return fall into four groups the IRS lists on its Gather your documents page: personal information, information returns (W-2s and 1099s), records for credits and deductions, and self-employment records. The checklist below follows those groups. For a tax practice, the better checklist is personal: start from what each client sent you last year, ask what changed, and email it in early January. Most forms arrive "electronically or by mail in January or February," according to the IRS.

Below you'll find the full checklist, then the per-client version our recipe sends, with its test results.

Not legal or professional-standards advice. We build and test automations; we're not lawyers or CPAs. Using a client's prior-year return information is regulated by Internal Revenue Code section 7216, and tax preparers fall under the FTC Safeguards Rule. Have counsel and your WISP owner review any automation before it touches client data. Checked October 28, 2026.

The 2026 tax document checklist (from the IRS list)

This follows the four groups on the IRS page (federal agency, last reviewed October 26, 2026). It is a starting point, not a complete list for every situation, and your state may need more.

Personal information

• Social Security number or ITIN for you and anyone else on your return
• Bank account and routing numbers for a direct-deposit refund or to pay what you owe
• Last year's adjusted gross income (AGI) and exact refund amount, if you filed
• Your name as the Social Security Administration has it, and your current address
• Your self-select PIN, if you e-filed last year
• Your Identity Protection PIN (IP PIN), if the IRS sent you one

Information returns (income forms)

• W-2 (or a corrected W-2) from each employer
• W-2G for lottery and gambling winnings
• 1099-K for payment card and online marketplace payments
• 1099-G for government payments such as unemployment
• 1099-INT for interest and 1099-DIV for dividends
• 1099-NEC for freelance and contractor work
• 1099-R for retirement plan distributions, pensions or annuities
• SSA-1099 for Social Security benefits
• 1099-MISC for other income
• 1095-A if you bought coverage through the Health Insurance Marketplace
• Records of digital asset transactions, if no form reported them

Credits and deductions

• Childcare or dependent care expenses
• Mortgage and property tax records (if you itemize)
• Charitable donations
• Health Savings Account or Flexible Spending Account contributions
• Healthcare expenses (if you itemize; special rules apply)
• Retirement contributions
• Education expenses for students and teachers: books, tuition and supplies

Side jobs and self-employment

• Statements from banks, payment apps, card processors or online marketplaces
• Checks paid to you
• Receipts and mileage logs for travel, gift and car expenses
• Records of deductible office expenses
• Estimated tax payments
• Other business income and expense records

Why a generic checklist isn't enough for your clients

Hand a client that list and they'll skim it, decide most of it doesn't apply and send half their forms in March. A personal list lands better: "Here's what we expect from you: your W-2 from Northwind Health and your 1099-INT from First Example Bank." The client can check it against their mail, and you can see at a glance what's missing.

You already have the data for that. Last year's return shows every payer. The job is turning it into one email per client, without exposing anything sensitive in the process.

Cheaper options to try first

1. Your tax software or practice-management tool. Many already produce organizers or client requests from prior-year data. Karbon, for example, lists automatic client reminders and client requests among its features (Karbon pricing, vendor page; Team plan from $59 per user per month billed annually). If yours does this, use it.
2. A mail merge. For 30 clients, a spreadsheet of last year's payers and a mail merge is an afternoon's work.
3. The recipe below, when you want the per-client lists sent on a schedule, account numbers masked automatically and every item fed into your document follow-up.

The per-client checklist, step by step

Our tax organizer checklist recipe runs in n8n on January 10:

1. Reads a Google Sheet you keep of what each individual client sent last year: form type, payer and any reference.
2. Builds one email per client listing what you expect this year, with the year rolled forward.
3. Masks account numbers to the last four digits and strips anything that looks like a Social Security number before the email is built.
4. Adds six yes/no life-change questions, because the list only knows what came in last year: a move, marriage, divorce or new child; a job change or side business; a home, stock or crypto sale; college, childcare or big gifts; an IRS or state letter; Marketplace coverage.
5. Points to your secure portal and asks clients not to email documents or their Social Security number.
6. Adds each item as a row in the document list that the document chase ladder recipe works from, so missing forms get polite reminders from there.
7. Opens a Karbon work item for the client's return if there isn't one yet (optional).
8. Sends the partner one summary: who got a checklist, who has no email on file and which work items were opened.

The test produced this email for an invented client:

Hi Ava,

It's tax season again. Based on what you sent us last year, here's what we expect to need for your 2026 return:

• 2026 W-2 (wages) from Northwind Health
• 2026 1099-INT (interest) from First Example Bank acct *7766

Most of these arrive by mid-February. Upload each one to your secure portal as it comes in.

The rest of the email holds the six questions, the portal link and the firm's name, phone number and address.

The compliance checklist before you turn it on

These rules are why the recipe masks data and keeps the email short. They're also why you should have someone check the setup.

• Section 7216: decide how the prior-year data may be used. The regulation says a preparer "may not disclose or use a taxpayer's tax return information prior to obtaining a written consent" unless the rules allow that use, and that consent "must be knowing and voluntary" (26 CFR 301.7216-3, federal regulation). Using last year's payers to prepare this year's return is a different question from sending that data to a marketing or AI tool. Ask counsel which side your setup falls on. We don't answer that for you.
• Safeguards Rule: encryption. The rule asks you to "protect by encryption all customer information held or transmitted by you both in transit over external networks and at rest" (16 CFR 314.4(c)(3), federal regulation). That's why the email carries no full account numbers and asks for uploads through the portal.
• Safeguards Rule: multi-factor authentication for anyone who accesses the n8n server, the Google Sheet or the email account (314.4(c)(5)).
• Your WISP lists every tool in the chain as a service provider: n8n and its server, Google, your email sender and Karbon. IRS Publication 4557 says that "tax return preparers must create and enact security plans to protect client data" and advises you to "encrypt all sensitive files/emails" (IRS Pub 4557, federal agency publication). Our WISP and automation post walks through it.
• A Qualified Individual is named to oversee the program (314.4(a)).
• No SSNs or full account numbers in any email, template or test file.

What it costs (illustrative)

Illustrative arithmetic, not a measured result. A firm with 150 individual clients sends 150 checklists once a year. Resend's free plan allows 3,000 emails a month but only 100 a day, so you'd split the send over two days. Its Pro plan is $20 a month for 50,000 emails, billed monthly (Resend pricing, vendor page). That works out to $0 to $20 a year for email, plus the n8n server you already run, and Karbon if you use it.

What we tested, and what we didn't

The recipe was run end to end in n8n against a local mock server, not live systems. The mock stands in for Google Sheets, Karbon and the email sender, and it replays Karbon's rate-limit responses. Every client is invented, nothing went to a real inbox, and the workflow uses no AI model.

The latest run (October 28, 2026) passed 3 of 3 scenarios:

• O1 (January 10): one checklist each for two clients, built from last year's documents. The account number was masked (*7766), a reference that looked like a Social Security number was removed, and the six questions were included. Four request rows were added for the chase ladder. A Karbon work item was opened only for the client who didn't have one, and one Karbon rate-limit reply (HTTP 429) was retried. The third client had no email on file, so no checklist went out; that client appeared in the partner summary instead.
• O2: running it again created no duplicate emails, rows or work items.
• O3: the next weekday, the document chase ladder picked up the new rows and sent each client a reminder for their outstanding items.

What we did not test: your real Google Sheet, Karbon account, portal or email deliverability, or how clients respond.

Related reading

• The accounting and bookkeeping hub lists every recipe for small firms, with the Safeguards Rule, WISP, 7216 and Circular 230 notes.
• The client document reminder email ladder covers the follow-up that starts after this checklist goes out.
• Once documents arrive, the waiting-on-client digest shows what's still outstanding, and the uncategorized transactions questions recipe handles the bookkeeping side.
• For billing, see the accounting invoice reminders recipe.
• Browse all recipes or the blog, or suggest a recipe.

Sources

All checked October 28, 2026.

1. IRS: Gather your documents (federal agency)
2. 26 CFR 301.7216-3, disclosure or use with the taxpayer's consent (federal regulation)
3. 16 CFR 314.4, Safeguards Rule elements (federal regulation)
4. IRS Publication 4557, Safeguarding Taxpayer Data (federal agency publication)
5. Resend: pricing (vendor pricing page)
6. Karbon: pricing and features (vendor pricing page)