The IRS Starts Issuing Cycle 4 Opinion Letters on August 31. Employers Then Have Two Years to Restate.

Most American 401(k) plans are not bespoke legal documents. They are standardised templates written by a bank, recordkeeper or law firm, blessed in advance by the IRS, and then adopted by thousands of employers who fill in the choices. Every six years the IRS reopens those templates, checks them against the law as it now stands, and re-approves them. Employers then have to sign the new version. That cycle has just reached its next date.

The dates

• August 31, 2026 — the IRS intends to begin issuing Cycle 4 opinion letters for defined contribution pre-approved plans, "or as soon as possible thereafter."
• October 1, 2026 — the window opens for adopting employers who have modified their document to request an individual determination letter, on Form 5307 or Form 5300.
• September 30, 2028 — the deadline for employers to adopt the newly approved Cycle 4 document, and the close of the determination-letter window.

What an opinion letter is, and what it is not

An opinion letter is the IRS's confirmation that the template document satisfies the qualification requirements of the tax code. It is issued to the provider that wrote the document, not to the employer using it. An employer that adopts the template without material change can generally rely on the provider's letter and does not need its own.

An employer that departs from the template far enough loses that reliance, which is what the determination-letter window is for. Form 5307 is the route for an adopter of a pre-approved plan; Form 5300 is the broader individually designed route.

What the cycle is catching up on

Cycle 4 documents were reviewed against the 2023 Cumulative List, published as Notice 2024-3 on December 20, 2023. A cumulative list is the IRS's inventory of the statutory and regulatory changes a document must reflect for that cycle. Restatement is how those changes get from the statute book into the plan an employer actually operates.

Who this does not apply to

The announcement covers defined contribution plans only — profit-sharing and 401(k) documents. Pre-approved defined benefit plans and 403(b) plans have their own remedial amendment cycles with their own dates, and are not affected.

A second change in the same bulletin

Rev. Proc. 2026-30, published alongside it, updates the procedures in Rev. Proc. 2026-4 for requesting letter rulings and nonbank trustee approval letters from the IRS Employee Plans Rulings and Agreements office. Applications must now be submitted electronically on pay.gov using Form 15662, rather than by mail or hand delivery.

Why it matters

Restatement is administrative, and it is also the moment when an employer's plan is legally re-papered. Savers rarely see it. What they may see is the paperwork that follows — a new summary plan description, or notice of changed provisions — arriving at some point over the next two years, because the document behind their account has been rewritten.