2027 Tax Season Kickoff: Key IRS Filing Dates and Law Changes for Preparers

6/15/2026

Every firm needs a season-opening briefing, and most firms build theirs from a webinar in mid-January — which is late, because by then the decisions the briefing should inform have already been made.

This post is about how to build one, and specifically how to build one that survives the thing that ruins season plans: guidance and forms that arrive after the season has started.

The Date Structure, and What Actually Moves

Four categories of date, with different reliability:

The season opening date — when returns can actually be transmitted — is announced each year and is not fixed. It has moved by weeks between years, and it is frequently later than firms assume. Do not build a workflow that assumes a specific opening date; build one that assumes a range and confirm it when announced.

Statutory deadlines are stable in structure and shift for weekends and holidays. Partnership and S corporation returns, individual returns, C corporation returns, and the extended dates each follow a pattern that holds year to year, with the actual calendar date confirmed annually.

Information return deadlines, which our post on 1099 and W-2 filing covers, differ by form and by whether the copy goes to the recipient or the agency.

Form and guidance availability, which is the category nobody plans for and which causes the most disruption. Specific forms are frequently not available at the season's opening, and returns containing them cannot be filed until they are. A firm that has not identified which of its clients depend on a late-released form will discover it while explaining a delay to that client.

The practical control: in December, identify the forms your client base actually needs, and check availability rather than assuming.

Where Season Changes Come From

Firms watch for legislation and miss three other sources that produce as much disruption.

Legislation, including anything enacted late in the prior year with retroactive effect — the worst case, because it can require amended returns for a season already underway.

Regulations and administrative guidance, including provisions where proposed rules were relied upon and final rules differ.

Expiring and sunsetting provisions, which change nothing about the law's text and everything about the return. A provision that lapsed produces a different answer than last year with no announcement, and this is the category most often missed because nobody publishes a headline about a provision simply ending.

Inflation adjustments, which change every threshold, limit, bracket, and phase-out. Individually minor, collectively the reason last year's planning spreadsheet is wrong.

Form redesigns and new schedules, which change where things go and break templates and workpapers.

State conformity decisions, which arrive on their own timelines and frequently after the federal season starts. A state that has not yet decided whether it conforms to a federal provision leaves returns for that state genuinely unfilable.

Build the Briefing From Primary Sources

A season briefing assembled from secondary summaries inherits their errors and their omissions. What to consult:

The agency's own filing season announcements and news releases, which state the opening date, known delays, and processing priorities.

Form and instruction availability lists, checked against your client base.

The applicable statutory and regulatory text for anything material, per the discipline in our post on tax research — and specifically not an AI summary, which will state provisions confidently as they existed in some prior period.

Your tax software vendor's release notes and known-issues list, which is the most underused source in the entire process. It tells you which forms are not yet supported, which calculations changed, and what is scheduled — and it is published before the season.

State revenue department announcements, for every state your firm files in.

Professional association updates, which are useful for flagging what to look at and should not be the citation.

The Firm Readiness Checklist

The work that has to be complete before returns start arriving.

Software. Installed, updated, prior-year data converted and verified — not assumed — and tested on a real return. Confirm which forms are not yet available and note the affected clients.

Templates and workpapers updated for form changes and for new limits. A template carrying last year's thresholds is a systematic error rather than an isolated one.

Engagement letters issued, signed, and tracked, per the discussion in our post on pre-season client acquisition. Work performed without a signed letter is a risk the firm accepted by default.

Information request lists issued, ideally generated from prior-year returns so the client is asked for what they actually had.

Preparer credentials current — identification numbers renewed, electronic filing credentials verified, and any state registrations confirmed. Renewals expire annually and a lapsed credential stops the firm rather than one person.

Continuing education completed, since a lapsed license in January is a firm-level problem.

Staff briefed on what changed, in a session with the changes written down rather than described.

Assignments and capacity set, per our post on capacity planning, including which engagements are already planned for extension.

The extension policy decided and communicated, in advance, so it is a plan rather than an apology.

Client Communications to Send Before January

Four messages, and sending them in December changes the season materially.

The information request, specific and dated, with a stated internal deadline and the consequence — after this date, the return is extended.

A short note on what changed that affects this client specifically. Not a general summary; a sentence about their situation. This is the communication clients actually value and almost no firm sends.

The extension expectation. Clients who are told in December that extension is routine and not a failure accept it. Clients who hear it in April experience it as the firm's shortcoming.

Fee and payment terms, agreed before work begins.

One addition worth making where the firm's client base includes anyone affected: a note that a specific form or state guidance is pending, so the delay is understood as external before it happens rather than explained afterward.

Structured coverage is available through the 1040 training courses catalog, the Individual Income Tax Preparation Course, the Small Business Income Tax Preparation Course, tax practitioner regulations, penalties, and security, the tax preparer certification courses listing, and ethics training and professional conduct.

Plan for Late Guidance

The part that distinguishes a firm that handles a disrupted season from one that is disrupted by it.

Identify the affected population in advance. For each pending item — a form, a state conformity decision, a regulation — know which clients it touches. That list is what lets you communicate proactively rather than reactively.

Sequence around it. Prepare what can be completed and hold only the affected returns, rather than holding whole categories of work.

Decide the amended-return posture before you need it. If a retroactive change arrives mid-season, will the firm amend affected returns, and at whose cost? Deciding that in February with a client on the phone produces inconsistent answers across the client base.

Extend deliberately where guidance is genuinely pending. Filing a return you expect to amend is usually worse than extending it, and the analysis in our post on extension strategy applies — with the reminder that an extension is not an extension of time to pay.

Log what you relied upon and when. Where a position depends on guidance current at the time, the file should show what was consulted and its date. This is both good practice and the support for a reasonable-cause position if the guidance later changes.

The First Two Weeks

A short discipline that prevents most early-season damage:

Test one return of each major type end to end before volume arrives — including electronic transmission and acknowledgment. Firms discover software problems on the client's return otherwise.

Confirm acknowledgments are being received and reviewed. A transmitted return that rejected and was not noticed is unfiled, and the discovery usually comes months later.

Reconcile the filed list against the acknowledgment list weekly, from the first week. This habit finds a small problem in week two instead of a serious one in April.

Watch for the first instance of each new form, and have someone competent review it rather than the preparer who is fastest.

Where Season Openings Go Wrong

Assuming an opening date rather than confirming the announcement
Not identifying which clients depend on a late-released form
Templates carrying prior-year thresholds, producing systematic errors
Ignoring the software vendor's known-issues list, which was published in advance
Missing an expiring provision, because nothing announced its end
Building the briefing from secondary summaries rather than primary sources
Using an AI summary for what changed, which will describe a prior period confidently
State conformity assumed rather than checked
Credentials or continuing education lapsed, stopping the firm rather than an individual
Engagement letters unsigned while work proceeds
The extension policy communicated in April rather than December
No amended-return posture decided in advance
Acknowledgments not reconciled, leaving returns unfiled and undiscovered
The client-specific "what changed" note never sent, which is the cheapest goodwill available

The summary for a firm in December: confirm the opening date when it is announced rather than planning around a guess, check form availability against your own client list, update templates for new limits, read your software vendor's known-issues list, and send the four December client communications. That is a season briefing, and it is worth more than any January webinar.

Frequently Asked Questions

Is the filing season opening date fixed?

No. It is announced each year, it has moved by weeks between years, and it is frequently later than firms assume. Workflows should be built around a range and confirmed when the announcement arrives, rather than assuming a specific date.

What causes the most season disruption?

Form and guidance availability. Specific forms are frequently unavailable when the season opens, and returns containing them cannot be filed until they are. The control is identifying in December which forms your client base actually needs and checking availability, so the affected clients are known before the delay rather than discovered during it.

Which source of change is most often missed?

Expiring and sunsetting provisions. Nothing is announced when a provision simply ends, so the law's text is unchanged and the return produces a different answer than last year. Inflation adjustments are a close second — individually minor, and collectively the reason last year's planning spreadsheet is wrong.

What is the most underused source for season preparation?

The tax software vendor's release notes and known-issues list, published before the season. It states which forms are not yet supported, which calculations changed, and what is scheduled — and firms routinely discover the same information by encountering it on a client's return instead.

What should clients be told in December?

Four things: a specific dated information request with the internal deadline and the consequence; a short note on what changed that affects them specifically, which almost no firm sends and clients value most; that extension is routine rather than a failure; and the fee and payment terms. Where a form or state guidance is pending for that client, say so before the delay rather than after.

How should a firm handle guidance that arrives mid-season?

Identify the affected client population in advance, sequence work so only affected returns are held, decide the amended-return posture — whether the firm will amend and at whose cost — before it is needed rather than with a client on the phone, extend deliberately where guidance is genuinely pending, and log what was relied upon and when.