A business return starts with a set of books that agrees to the bank, the payroll returns and the prior-year return. This checklist covers the common documents for a 2026 Form 1120, 1120-S or 1065 return, grouped by what the firm needs first: the entity and ownership details, the year-end books, the balance sheet support, and the payroll and 1099 records. Optional items apply only to some entity types.
Who sends itSent by the tax preparer to each business client after the year ends and before the return is prepared. The firm sets one due date for the organizer and follows up on the items that decide the return.
Reviewed November 3, 2026 · 39 items
0 of 39 ticked
01Entity and ownership
02Year-end books
03Balance sheet support
04Payroll and owners
051099s and vendors
06Tax positions and questions
What firms get wrong
Sending one organizer to every entity type, so an S corporation is asked for partnership items and a partnership is asked for W-2 details.
Waiting for the final trial balance before asking for the bank statements, payroll returns and asset invoices.
Missing the prior-year depreciation schedule, which makes every asset addition a new decision.
Forgetting the owner health insurance and draws, which change the owner's return even when the business return is correct.
Assuming the prior-year return's entity type is still correct after an ownership change.
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Questions about this checklist
What is a business tax organizer?
It is the list of records the firm needs to prepare a business return: the year-end books, the ownership details, the balance sheet support, payroll records and the 1099 information. A good organizer asks the client only for what applies to the entity.
Which form does a business file?
A partnership files Form 1065, an S corporation files Form 1120-S and a C corporation files Form 1120. The entity type on the prior-year return decides the form, so send the prior return with the organizer.
What if the books are not closed when the organizer is due?
Send the organizer anyway. The client can provide the bank statements, payroll records and asset purchases while the bookkeeper finishes the close, and the firm can start on the parts that do not depend on the final trial balance.
When is a calendar-year business return due?
A calendar-year Form 1065 or Form 1120-S is generally due March 15, 2027 for tax year 2026. A calendar-year Form 1120 is generally due April 15, 2027. An extension changes the filing date but not the date the tax is due.
What does an S corporation need that a partnership does not?
An S corporation needs the owners' W-2 wages and reasonable compensation support, and the health insurance paid for owners who own 2% or more. A partnership needs the partners' capital accounts and distribution details instead.