What to send your tax pro before busy season: a document checklist

Busy season arrives on the same calendar every year, and the same documents arrive late every year: K-1s, corrected 1099s, closing statements, basis schedules sitting in someone's personal email, foreign account statements that "will come later." A return can only be as accurate as the documents behind it. The households that file cleanly are the ones that assembled the pack before January.

This post is a document checklist for the 2026 tax year (returns filed in 2027) for households with more than one state, entity, or income stream. It covers what to gather, how to organize it, and when to send it. Your preparer may want more or less. Ask them, and use this list to fill the gaps.

Why "we'll send everything in March" fails

A household with one W-2 can survive late documents. A household with pass-through investments, a trust, foreign accounts, a household employee, non-cash charitable gifts, and returns in three states cannot. Late documents create three problems: the return goes on extension by default, estimated payments get set without real numbers, and errors show up later as amended returns and notices.

Preparer capacity in February and March is finite. A complete, indexed pack gets review time. Files that trickle in through April get processing time.

A working calendar for the 2026 tax year

• November and December 2026: Build the folder structure. Request missing basis reports. Confirm that year-end charitable gifts are actually completed, not pledged. Ask fund sponsors whether they publish estimated K-1 ranges. Record any change of address or residency.
• January 2027: W-2s and Forms 1099-NEC are due to recipients by February 1, 2027 (January 31 falls on a Sunday). Collect mortgage interest, property tax, household payroll year-end reports, and December foreign account statements as they arrive.
• Mid-February 2027: Consolidated brokerage 1099s typically arrive around now, and corrected versions often follow. Send the first full batch to your preparer: everything except items you know will come later.
• March and April 2027: Partnership and S corporation returns are due March 15, 2027, but many K-1s arrive on extension. Individual returns and extension payments are due April 15, 2027.
• Summer through October 2027: Extended partnership returns are due September 15, 2027. Extended individual returns are due October 15, 2027.

Treat mid-February as the target date for everything that is not a K-1. Confirm the exact dates with your preparer in writing.

Folder structure

Create one folder for the tax year (TY2026) with numbered subfolders. Consistency matters more than the names. A workable set:

• 01 Organizer and ID
• 02 W-2 and 1099 income
• 03 Brokerage and digital assets
• 04 K-1s (partnerships, S corporations, trusts)
• 05 Real estate and rentals
• 06 Entities you own
• 07 Foreign accounts and entities
• 08 Charitable gifts
• 09 Household employees
• 10 Medical, education, dependents
• 11 Interest and taxes paid
• 12 Estimated payments and withholding
• 13 Multi-state presence records
• 14 Life events and legal documents
• 15 Basis schedules and carryforwards
• 16 IRS and state notices

Deliver through the secure portal or encrypted upload link your preparer provides. Do not send tax documents by plain email or text message.

The core checklist

Mark each item present, not applicable, or still chasing.

Organizer and identity

• Completed organizer or questionnaire
• Prior-year federal and state returns (required if you changed preparers)
• Names, SSNs or ITINs, and birthdates for dependents, plus custody arrangements if relevant
• Bank details for refunds and payments
• Who the preparer should contact, and who can authorize decisions

Compensation and retirement

• All W-2s, including any from a closely held company you own
• Forms 1099-R for pension and IRA distributions
• Equity compensation statements: vest confirmations, exercise records, and supplemental basis reports
• Deferred compensation payout statements
• Director fee reporting (1099-NEC or W-2)

Investment income

• Consolidated 1099 from every custodian
• Any 1099-INT, DIV, B, or MISC issued separately
• Realized gain and loss reports, with adjusted basis reviewed for obvious gaps
• Digital asset year-end reports and cost-basis exports. Brokers report gross proceeds on Form 1099-DA for sales from 2025 on, but basis reporting covers only assets acquired at that broker in 2026 or later, so your own basis records still matter.
• Interest ledgers for private notes
• State-by-state detail for tax-exempt interest

Pass-throughs and trusts

• A K-1 tracker (see below)
• Final federal K-1s with all footnotes and state K-1s
• Grantor trust letters and trust K-1s
• Partner basis and S corporation stock and debt basis schedules through the prior year
• Passive activity and at-risk carryforward schedules

Real estate

• Rental income and expense ledgers by property
• Closing statements for purchases, sales, and refinances
• Form 1098 mortgage interest
• Property tax bills with proof of the payment date. For 2026 the federal SALT deduction cap is $40,400, reduced for modified AGI above $505,000 (not below $10,000), so the year of payment matters.
• Depreciation schedules and any cost segregation study
• Personal use and rental day logs for any vacation or mixed-use property
• Invoices for improvements that add to basis

Household employees

• Payroll provider year-end reports, W-2s, and W-3
• State unemployment filings
• Records showing cash wages per worker. For 2026, Social Security and Medicare apply once you pay any one household employee $3,000 or more in cash wages, and Schedule H is filed with your Form 1040.

Charitable gifts

• Written acknowledgments for every gift of $250 or more
• Non-cash gift receipts, and qualified appraisals where required (generally non-cash gifts over $5,000)
• Donor-advised fund contribution confirmations
• Stock gift transfer confirmations with dates

Two 2026 changes make receipts matter more. Itemizers now deduct only the portion of charitable gifts above 0.5% of AGI. Non-itemizers can deduct up to $1,000 ($2,000 joint) of cash gifts to public charities, though not gifts to donor-advised funds. Your preparer needs the full list to choose the better treatment.

Foreign accounts and entities

• A list of every foreign account with its maximum value during the year. FBAR filing applies when the combined maximum value exceeds $10,000 at any point.
• Statements supporting the Form 8938 thresholds (for a married couple living in the U.S., more than $100,000 at year-end or $150,000 at any time)
• Ownership charts for foreign entities, and the data packages needed for Forms 5471, 8865, or 8858
• Foreign tax paid documentation

Multi-state

• A day-by-day presence calendar (see the residency and domicile post)
• Where remote work was performed
• Property list by state
• Nonresident withholding statements
• Prior-year state returns

Payments and credits

• Federal and state estimated payment confirmations with dates and amounts
• Prior-year overpayments applied
• IRA and HSA contribution records
• Documents for any credits claimed

Life events and legal

• Marriage, divorce, or separation agreements
• Closing binders for any business sale
• Settlement agreements and related 1099s
• Prior gift tax returns and a current-year gift ledger. The 2026 annual exclusion is $19,000 per recipient. Gifts above that to any one person generally require Form 709.
• Trust amendments that could change grantor status

Add-on for entities you own

• Trial balance and year-end financial statements
• Bank reconciliations
• Payroll filings and owner compensation detail
• A log of related-party transactions (rent, loans, shared staff)
• Fixed asset register
• Debt schedule
• Ownership changes during the year
• State apportionment workpapers and franchise tax confirmations
• Forms 1099-NEC and 1099-MISC issued. For payments made in 2026, the general threshold rose from $600 to $2,000.

Messy books are a tax risk on their own. If the entity's bookkeeping is not closed, the K-1 it issues will not be right either.

The K-1 tracker

A simple spreadsheet with one row per entity:

• Legal name and EIN
• Tax classification (partnership, S corporation, trust)
• Ownership percentage
• Sponsor contact
• Expected arrival date and date received
• States listed in the footnotes
• Prior-year ordinary income, rounded
• Location of the basis schedule
• Notes

Review it every two weeks from August through October. Contact sponsors early. If a K-1 has not arrived by the time you are setting the extension payment, the payment needs a cushion.

How to deliver

• One upload batch with an index listing every file
• Descriptive file names: 2026_Schwab_1099.pdf, not scan002.pdf
• Final documents kept separate from drafts and estimates
• Version notes when you replace a file
• A cover note listing known gaps: "Missing: Fund B K-1, expected September 1, return will extend."
• The presence calendar and estimated payment ledger in the first batch, even if the return will extend

Scored diagnostic

Score each question 0, 1, or 2. Total possible: 30.

#	Question	Score
1	Was the non-K-1 pack delivered by the agreed date last year?
2	Is there a current K-1 tracker?
3	Are basis and carryforward schedules stored in one place?
4	Is there a complete list of foreign accounts with maximum values?
5	Are household payroll documents included without a separate chase?
6	Are file names standardized and indexed?
7	Are brokerage basis reports reviewed before sending?
8	Are mixed-use property logs kept during the year, not rebuilt afterward?
9	Are corrected forms tracked and re-sent with a note?
10	Is delivery through a secure channel only?
11	Are IRS and state notices sent to the preparer within a few days of receipt?
12	Are due dates agreed with the preparer in writing?
13	Is one person responsible for coordinating the pack?
14	Is the extension decision planned rather than a default?
15	Is the final pack archived after filing?

Below 18 means the pack is being assembled under deadline pressure. Start with items 2, 3, and 13.

A short kickoff call

Thirty minutes with your preparer in November covers most surprises:

• New entities and investments this year
• Any change in residency or new states
• Large sales, exercises, or distributions, completed or planned
• Pack due dates and the extension plan
• Last year's problems: late K-1s, missing basis, notices
• How documents will be delivered

What not to send, or how not to send it

• Passwords in the same email as the encrypted file
• Years of irrelevant history without asking first
• Bad news held back: notices, divorce decrees, or a settlement belong in the first batch
• Assumptions that a former preparer's files transferred when you changed firms

Organizer questions deserve slow answers

Organizers ask yes or no questions that people answer quickly. "Did you give gifts over the annual exclusion?" "Do you have foreign accounts?" "Did you sell property?" A wrong "no" becomes a filing position. If you are unsure, write "discuss" and attach the ledger.

Corrected forms

Brokerages issue corrected 1099s and funds issue amended K-1s, often after a draft return exists. Keep a corrections subfolder with dates, and tell your preparer explicitly when a correction arrives. Silently replacing a file in a shared folder is how filed numbers drift from the final forms.

Illustrative example

Illustrative: A household uploads 400 unsorted phone photos on April 10. The preparer spends billable hours classifying them. Two foreign accounts never appear in the upload, the extension payment is set without them, and an FBAR is missed. The following year the household builds the folders in November, sends an indexed batch in February, and names one person to coordinate. Fees go down and the missed filing does not repeat.

After filing: keep the archive

Once the returns are filed, save a read-only copy of the returns, the pack as delivered, payment confirmations, and e-file authorizations. Basis questions come up years later in sales, gift tax reviews, and estate administration. The IRS generally has three years to assess, six in some cases of substantial omission. Basis records for property you still own should be kept until it is sold and the assessment period for the year of sale has closed.

Where to start

Build the folder structure this November. Start the K-1 tracker. Book the kickoff call. If income will arrive unevenly next year, read estimated taxes when income is lumpy next.

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Educational only. This is not tax or legal advice for your situation. Consult your own CPA, EA, or attorney before acting.