S Corp Tax Documents Checklist (Form 1120-S) | HelloBooks S corp tax documents checklist for Form 1120-S: books and bank records, shareholder details for K-1s, officer pay, distributions and basis records for Form 7203.
An S corporation return needs the company’s books plus a layer of shareholder information. Collect both together, because the K-1s and the shareholders’ basis work depend on the same figures.
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The Instructions for Form 1120-S (2025) set the due date as the 15th day of the 3rd month after the tax year ends; for calendar-year corporations that was March 16, 2026, because March 15 fell on a Sunday. Schedule K-1s must reach shareholders on time, and the instructions set a penalty for each failure to furnish one.
Start collection early in January so the books can close before the K-1 work begins.
Form 7203 is used by S corporation shareholders to figure the potential limits on their share of the corporation’s deductions, credits and other items. Ask for prior-year basis schedules and every contribution, distribution and loan during the year.
With the company’s books in HelloBooks and reconciled monthly, the year-end request is mostly shareholder information. Distributions and shareholder loans show as their own accounts in the ledger, which saves the usual back-and-forth.
General information for tax and accounting professionals, not legal advice. Rules are summarised from the primary sources listed on the date shown; read the current text before relying on it.
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