Guide

Tax Season Preparation Checklist for CPA Firms (2027)

A month-by-month checklist covering everything from November staff planning through May post-season cleanup. Designed for CPA firms of all sizes handling individual and business returns.

Last updated: April 2026

What are the key tax dates for 2027?

January 31, 2027W-2 and 1099 issuance deadline for employers
March 15, 2027S-Corp (1120-S) and Partnership (1065) filing deadline
April 15, 2027Individual (1040) and C-Corp (1120) filing deadline
April 15, 2027Extension filing deadline (Form 4868, Form 7004)
June 15, 2027Q2 estimated tax payment deadline
September 15, 2027Extended S-Corp and Partnership filing deadline
September 15, 2027Q3 estimated tax payment deadline
October 15, 2027Extended individual (1040) filing deadline

November 2026

Strategic planning month. Staff planning, software updates, engagement letter renewals, and client outreach.

  • Review and finalize staffing plan for the upcoming season
  • Update all tax preparation software and document management tools
  • Draft and send engagement letter renewals to returning clients
  • Review IRS updates and tax law changes for the 2026 tax year

December 2026

Preparation execution month. Get engagement letters signed, portals set up, and organizers ready to send in January.

  • December 15: Target date for all engagement letters sent
  • Set up client portal access for new and returning clients
  • Pre-schedule January organizer distribution
  • Send year-end tax planning reminders to clients

January 2027

Collection sprint. W-2s and 1099s are issued this month. Get organizers out immediately.

  • January 3: Send client organizers and document requests
  • January 15: First round of automated document reminders
  • January 31: Employer deadline for issuing W-2s and 1099s
  • Begin identifying extension candidates (missing K-1s, complex situations)

February 2027

Primary collection and preparation month. Most documents should be arriving.

  • February 1-7: Second round of document reminders
  • Mid-February: 1099-B and brokerage statements begin arriving
  • Begin return preparation for clients with complete documents
  • February 20-28: Third round of reminders with increased urgency

March 2027

The push. Focus on completing returns, extension prep, and final document collection.

  • March 1-7: Final reminder round for outstanding documents
  • March 15: S-Corp and Partnership returns due (Form 1120-S, 1065)
  • March 20: Finalize extension decisions with clients
  • File completed returns on a rolling basis (do not batch)

April-May 2027

Final filing push, post-season cleanup, and extension return preparation.

  • April 15, 2027: Individual return filing deadline (Form 1040)
  • April 15, 2027: Extension deadline (Form 4868) and estimated tax payments due
  • April 16-30: Send filing confirmations, address e-file rejections
  • May: Season retrospective, record retention, begin extension return prep
  • October 15, 2027: Extended return filing deadline

How can technology streamline this checklist?

The biggest time sink in this checklist is document collection and client follow-up. Across the entire season, firms spend an average of 90 minutes per client on document collection alone. For a firm with 200 clients, that is 300+ hours of administrative work.

Taxhance automates the most labor-intensive items on this checklist: document request distribution, automated reminder cadences, AI-powered document classification, real-time status dashboards, and secure client communication. Instead of manually tracking which clients have submitted which documents, your team focuses on preparing returns.

Features like the compliance calendar track every date listed above and send your team proactive notifications. Document checklists ensure every client knows exactly what to submit. And role-based access keeps your team organized even during the busiest weeks.

Frequently Asked Questions

When should CPA firms start preparing for tax season?
The best firms begin preparation in November, at least two months before the January filing season begins. November and December are used for staff planning, software updates, engagement letter renewals, and client outreach. Firms that wait until January to prepare consistently report higher stress levels and more missed deadlines.
What is the most common mistake firms make during tax season preparation?
Waiting too long to send client organizers and document requests. Firms that send organizers in the first week of January (or even late December) collect documents faster and have fewer last-minute extensions. Every week of delay in January compounds the backlog in March and April.
How many reminder emails should a firm send for outstanding documents?
Industry best practice is 3-5 reminders per client over a 6-8 week window. Start with a friendly initial request, follow up at 2 weeks, then weekly as the filing deadline approaches. Automated reminder systems like Taxhance handle this cadence without manual effort.
When is the last day to file 2026 individual tax returns?
The standard deadline for 2026 individual tax returns (for tax year 2025) is April 15, 2027. If April 15 falls on a weekend or holiday, the deadline moves to the next business day. The extension deadline for individual returns is October 15, 2027.
How long should CPA firms retain tax documents?
The IRS generally recommends retaining tax returns and supporting documents for at least 3 years from the filing date or 2 years from the date the tax was paid, whichever is later. However, many CPAs recommend a 7-year retention policy to cover potential audit windows, and some documents related to property or investments should be kept indefinitely.
What tools help CPA firms manage tax season preparation?
Modern CPA firms use a combination of tax preparation software (UltraTax, Lacerte, Drake, ProConnect), document management platforms (like Taxhance for AI-powered collection and classification), project management tools, and secure client communication portals. The key is having a centralized system that reduces manual tracking.

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