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K-1 Infrastructure Series Part 4: The 401(k) Wave and the K-1 Wall

BY Scott Turner

August 28

The 401(k) Wave and the K-1 Wall

In brief: The comforting assumption — retirement savers will never see a K-1, so the K-1 problem is not a retirement problem — has it backwards. Complexity that savers never see does not disappear; it moves into the retirement system, where tolerance for ambiguity is lowest. A modest allocation shift could add roughly 20 million K-1s above baseline by 2028, arriving through intermediaries with fiduciary expectations the current infrastructure was never designed to meet.

As alternative investments move toward 401(k) plans, there is a reassurance being passed around the industry: the average retirement saver will never personally receive a Schedule K-1, so the K-1 problem is not really a retirement problem.

The first half of that sentence is true. The conclusion drawn from it is wrong — and the way it is wrong is exactly why the industry should be paying attention now.

Depending on structure, the tax reporting may be absorbed at the plan, vehicle, administrator, trust, platform, or intermediary level. But complexity absorbed is not complexity eliminated. It moves. Somewhere in the retirement system, someone has to handle the reporting, reconciliation, permissions, corrections, tax attributes, auditability, and downstream data consequences created by private-market structures.

The K-1 problem does not become irrelevant when private markets enter retirement channels. It becomes more consequential — because the tolerance for ambiguity goes down. Institutional investors can absorb friction. Mass retirement infrastructure cannot casually depend on it.

To see why this is a present question rather than a distant one, start with how the current system got away with it — and then with a number.

A world built on absorbed complexity

Private markets were built for sophisticated participants. That does not mean they were simple. It means the complexity was mostly absorbed by institutions, family offices, fund administrators, tax advisors, and professional investors who knew what they were signing up for.

A wealthy LP might complain about K-1 chaos, but they usually had people to chase the documents. A family office might hate the portal scavenger hunt, but it had staff. A large institution might push for better process, but it had operations teams. A CPA firm might get crushed every spring, but the market had learned to call that seasonality.

That world is changing. Private equity, private credit, real estate, infrastructure, and other alternatives are no longer only a conversation for institutions and the ultra-wealthy. They are increasingly part of the policy, fiduciary, and product conversation around defined-contribution retirement plans. The policy direction is already visible: an August 2025 executive order called for expanded access to alternative assets in 401(k)-style plans, and in March 2026 the Department of Labor proposed a process-based framework for fiduciaries considering alternatives in participant-directed plans.

The investment debate — fees, liquidity, valuation, suitability — will get most of the attention. Those questions matter. But beneath them sits a quieter one: can the operational and tax-data infrastructure handle the wave?

A number worth guessing

There is roughly $10 trillion sitting in 401(k) plans today. Suppose a modest 10% allocation shift toward alternatives — well within the policy direction now visible. That moves $1 trillion into K-1-generating structures.

Before reading on, take a guess: how many additional K-1s does that trillion dollars create?

The instinct is to reason from institutional experience, where a trillion dollars is spread across a few thousand large positions. It is also tempting to reason from participant counts — but that is exactly the mistake the industry’s own reassurance rules out: where a plan holds a partnership interest, the K-1 goes to the plan’s trust, and the participant sees a 1099-R. The volume driver is not savers. It is the plumbing built to keep K-1s away from savers — feeder vehicles, SPVs, fund-of-fund layers, custodial positions in the IRA channel — each an entity-level, K-1-generating position, and each far smaller than an institutional allocation. At an estimated $50,000 average per K-1-generating position across that intermediation stack, $1 trillion translates into roughly 20 million additional K-1s above baseline by 2028.

For context: the IRS logged about 45 million K-1s filed in 2024. One structural driver, at one plausible allocation level, adds nearly half of today’s entire market on top of the organic growth the IRS was already projecting. That is the long-term planning case, not the optimistic one — and it is the dominant structural driver behind the 2028 planning case of roughly 71 million K-1s. The broader retailization of alternatives through wealth channels compounds steadily on top, but the 401(k) channel supplies most of the increment above the IRS baseline.

The wave lands on a system already under stress

That growth does not land on a clean operating model. It lands on an ecosystem still dependent on PDFs, portals, zip files, emails, inconsistent footnotes, ad hoc downloads, manual versioning, correction loops, and downstream reconstruction — a model that has survived because professional intermediaries absorbed the pain.

And it is not just a volume problem. A 20-million-K-1 increase arriving through new intermediaries — with new fiduciary expectations, new reporting structures, new timing requirements, and new questions from participants, advisors, sponsors, platforms, and regulators — is qualitatively different from the same volume arriving through the existing institutional channel.

The marginal K-1 is not merely one more file. It is one more entitlement question. One more correction path. One more chain-of-custody requirement. One more audit trail. One more piece of tax data that may need to flow through systems that were not designed for it.

That is how systems buckle. Not because one thing breaks — because every seam gets pulled at once.

Retirement changes the standard of care

Private-market tax reporting has historically been an institutional workflow challenge. Retirement access changes the standard.

Once alternative assets are included in defined-contribution structures, the system has to support participants whose financial lives depend on the quality of fiduciary process and infrastructure decisions they will never personally see. It is no longer enough for the industry to say sophisticated participants can manage the complexity. The industry must be able to show that the complexity is governed, auditable, controlled, and operationally scalable.

When private markets intersect with retirement savings, government scrutiny is inevitable — and it will not be limited to investment selection. It will include process, governance, valuation, liquidity, documentation, risk controls, and operational evidence. Tax reporting infrastructure sits underneath all of it. If reporting is late, inconsistent, opaque, or overly dependent on manual processes, the industry will eventually have to explain why it invited private-market complexity into retirement channels without modernizing the information rails that support it.

The industry can treat the policy opening as an investment-product opportunity only. Or it can recognize it as an infrastructure readiness test.

AI arrives into the same mess

The timing matters for one more reason: AI is arriving at exactly the moment the system is becoming more complex.

AI will read K-1s faster, summarize footnotes, extract fields, classify attributes, compare versions, and power new advisory products. But without standards, permissioning, provenance, and auditability, AI also creates new risks. It may process the wrong version. It may infer meaning from inconsistent footnotes. It may operate on data without clear consent. It may generate confidence where the source chain is weak.

AI needs networks and standards to become trustworthy at industry scale. Otherwise, it accelerates fragmentation.

Rails before heroics

The industry should not wait for the retirement wave to expose the weakness of the current model. It should build the rails now.

A governed exchange layer would not eliminate tax complexity or remove the need for fiduciaries, advisors, CPAs, administrators, or platforms. It would do something more basic and more valuable: create a trusted way for K-1 and related data to move between authorized parties with standards, permissions, version control, correction handling, delivery status, and auditability.

That is what scaling requires. Not more seasonal heroics. Not more portals. Rails.

The choice before the industry

Private markets are being invited into the retirement system. The tax infrastructure has not yet been invited to grow up. That gap is both the opportunity and the risk.

If the industry acts now, it can build a governed, market-led infrastructure layer that supports growth, protects participants, improves fiduciary evidence, enables AI, and frees capacity back into the system. If it waits, the problem will not stay hidden inside back offices. It will show up as delays, avoidable cost, weak controls, participant anxiety, and regulatory pressure.

So return to the reassurance we opened with. It is true that the saver may never see a K-1. That was never the question. The question is whether the system behind the saver can absorb what the saver never sees — at 20 million additional documents landing on trusts, custodians, and administrators rather than savers, under a fiduciary standard of care, on infrastructure built for a smaller and more forgiving world.

The industry can govern itself thoughtfully now. Or be governed later by people responding to the last failure.

That is the K-1 wall.

Sources: Executive Order 14330, “Democratizing Access to Alternative Assets for 401(k) Investors,” White House, Aug. 7, 2025; U.S. Department of Labor proposed rule and Federal Register notice, Mar. 30–31, 2026; Reuters coverage, Mar. 30, 2026. K-1 volume baseline: IRS Statistics of Income, Publication 6961 (~45M K-1s filed, 2024; ~50M projected by 2028). The $10T 401(k) asset base, 10% allocation scenario, $50K average entity-level K-1-generating position size, ~20M incremental K-1s, and ~71M 2028 planning case are internal planning estimates and should be read as scenarios, not forecasts.

Now read article 5: Common Rails for a Common Problem

About Author

Aaron Bartrim has spent his career at the intersection of technology and people, building systems that enable entire industries.

As CTO of Early Warning Services, he led the build-out of Zelle®, taking real-time payments from concept to a network serving more than 1,000 financial institutions, proving that speed and safety aren’t a trade-off when the system is designed for both. Earlier, as CTO of eFunds and a senior leader at FIS, he built the payments and integration infrastructure connecting banks to their customers. As CTO of Capital Markets Gateway, he brought that same discipline to equity capital markets, replacing decades of manual workflows with a connected digital platform.

Few technologists have taken an entire industry through that kind of change more than once. That experience of enablement at scale, done safely, is the lens he brings to AI: the next system industries will quietly depend on.