The Trustee's Guide to Prudent Investment Management

Serving as a trustee is an honor that arrives with real legal weight. Whether you're a family member named in a parent's trust, a professional fiduciary, or an officer of a trust company, you're responsible for managing assets that belong to someone else — under standards courts take seriously.

Here's a plain-English guide to what prudent investment management means for a trustee, and how to build a process that protects both beneficiaries and you. State law differs on some of the specifics below, and none of this is legal advice for a particular trust — but the underlying principles hold in almost every jurisdiction that applies a prudent-investor standard.

Understand the standard you're held to

Nearly every state has adopted the Uniform Prudent Investor Act (UPIA) or a substantially similar prudent-investor statute; Delaware is a notable exception, applying its own prudent-person statute rather than the model act. Wherever it applies, three ideas do the real work:

• The portfolio is judged as a whole, not investment by investment. A single holding isn't imprudent in isolation; the question is whether the overall strategy fits the trust's purposes and its risk and return objectives.
• Process matters more than outcome. Markets fall; that alone doesn't make a trustee imprudent. Failing to have — and follow — a sensible, documented process does.
• The trust's purposes govern. The right portfolio depends on what the trust exists to do: support a surviving spouse, fund grandchildren's education, preserve principal for a remainder beneficiary, sustain charitable giving.

The UPIA also spells out the specific factors a trustee is expected to weigh, and they double as a useful working checklist: general economic conditions; the possible effect of inflation or deflation; the expected tax consequences of a given strategy; the role each holding plays within the overall portfolio; expected total return from income and appreciation combined; the beneficiaries' other resources; their need for liquidity, regular income, or preservation of capital; and whether a particular asset holds special value to the trust's purposes or to a specific beneficiary. No single factor is decisive — a trustee is expected to weigh them together and be able to explain the weighing later.

Take the duty of impartiality seriously

Many trusts have current beneficiaries who receive income or distributions and remainder beneficiaries who inherit later. Their interests conflict: one favors income today, the other growth for tomorrow. In the large majority of states — those that have adopted the Uniform Trust Code — this tension is codified directly: a trustee with two or more beneficiaries must act impartially in investing, managing, and distributing trust property, giving due regard to their differing interests. In practice this usually argues for a diversified, total-return approach rather than tilting the portfolio toward whichever beneficiary calls most often.

Impartiality, like diversification, is a default rule. A settlor can direct a trustee to favor one class of beneficiary over another — but only if the trust instrument says so clearly. Absent that kind of express instruction, a trustee who leans hard toward one side, even with good intentions, is exactly the trustee this standard is designed to catch. If you feel pulled toward one beneficiary, that's precisely when the standard matters most.

Diversify — especially the inherited concentration

Trusts frequently arrive holding concentrated positions: founder stock, the family business, a large low-basis holding a grantor loved. The prudent investor standard creates a general duty to diversify unless the trustee reasonably determines that special circumstances — often tax exposure on a highly appreciated position, or a genuine wish to preserve a family enterprise — justify concentration. Concentration decisions, including a decision to hold, deserve explicit analysis and documentation. "Grandfather bought it and we never sold" is a sentiment, not a process.

The diversification duty, like impartiality, yields to the trust instrument — and getting the direction of that deference wrong can be costly in either direction. In an unpublished 2018 New Jersey appellate decision, In re Trust of Ray D. Post — not binding precedent, but instructive on the principle — a corporate trustee sold down a concentrated stock position that the trust instrument had directed it to retain "without liability for loss or depreciation," reasoning that the state's prudent investor statute obligated diversification as routine good practice. Both the trial court and the appellate court disagreed: the statutory duty to diversify is a default rule a settlor can override, and a trustee who wants to depart from clear retention language — even in the name of prudent diversification — needs beneficiary consent or court authorization first. The trustee was held liable for the resulting losses. The lesson isn't "always diversify" or "always retain." It's that the instrument's express terms control, and departing from them without documented authorization is where trustees get into trouble in either direction.

Put it in writing: the trust IPS

An Investment Policy Statement tailored to the trust — its purposes, distribution requirements, time horizon, tax situation, and any instrument-specific constraints — converts good intentions into a defensible process. It also makes every later decision easier: new circumstances get measured against a written standard rather than re-argued from scratch.

Document decisions as you go

Meeting notes, review summaries, the reasoning behind major decisions — kept contemporaneously, not reconstructed later. If a beneficiary ever questions your management, the file you built is your answer. Trustees rarely regret documenting too much.

Coordinate the tax layers

Trust taxation is unforgiving. For 2026, a non-grantor trust reaches the top 37% federal bracket — and triggers the 3.8% net investment income tax on income the trust doesn't distribute — at just $16,000 of taxable income, a fraction of the roughly $640,000-plus threshold that applies before an individual filer reaches the same top bracket. That compression alone makes distribution timing a live tax lever, not just an administrative one: income distributed to a beneficiary is generally taxed at the beneficiary's own, often lower, rate rather than the trust's.

Principal-and-income accounting adds a second layer: which receipts count as income for the current beneficiary and which count as principal for the remainder beneficiary affects what each side actually receives, separate from the trust's overall investment return. Most states now give a trustee some power to adjust between principal and income so a total-return investment strategy doesn't inadvertently shortchange one side — a tool worth understanding rather than defaulting away from. None of this should be handled in a silo: investment strategy and distribution decisions need to be coordinated with the trust's CPA before they're made, not after.

Delegate prudently — it's allowed, and often wise

Modern trust law permits trustees to delegate investment management to qualified professionals, and the standard for doing so well is specific: reasonable care in selecting the agent, in setting the scope of what's delegated, and in periodically reviewing the agent's performance against that scope. Meet all three, and the protection is real — a trustee who satisfies that standard is generally not liable for the delegate's investment decisions themselves. Skip any of the three, and the delegation itself becomes the exposure.

That's why many trustees choose to delegate: it lets them meet their oversight duty — selecting, directing, and monitoring a manager — without taking on day-to-day portfolio management personally. Delegation done well is not an abdication; it's a documented decision like any other.

Where we fit

TAGStone Capital serves as investment manager for trusts and their trustees — building IPS-driven, documented, tax-aware portfolios, and coordinating with trust counsel and CPAs on distributions and administration. As a fee-only fiduciary, our only compensation comes from our clients, which keeps our interests aligned with the beneficiaries you serve.

Serving as trustee and want a documented, defensible investment process? Let's talk. Schedule a conversation