MLPs in an Irrevocable Trust: When the Tax Shelter Becomes the Tax Problem

Your estate attorney structured an irrevocable trust to protect your assets and reduce your estate tax exposure. It was good advice — for your stocks, your real estate, and your cash. For your MLPs, it may have created a problem worth more than the solution.

Here’s what happens when MLP positions sit inside an irrevocable trust: the trust pays federal income tax at the highest rate on just$15,650 of taxable income (versus $751,600 for an MFJ couple). The MLPs may generate unrelated business taxable income that requires Form 990-T. The trust must file K-1s in every state where the MLPs operate. And depending on the trust type, your beneficiaries may not receive the §1014 basis step-up that would have eliminated decades of deferred tax and §751 recapture.

This is the most technical article in the estate-planning cluster. It’s written for the person whose attorney placed MLPs in an IDGT, credit-shelter trust, or dynasty trust without modeling the K-1/UBTI/step-up consequences — and for the CPAs and attorneys who need the computed numbers to have the conversation.

The core problem is structural. Irrevocable trusts use their own federal income tax brackets under IRC §1(e) — brackets compressed so aggressively that the top 37% rate kicks in at$15,650. For comparison, an MFJ couple doesn’t hit 37% until$751,600.

For MLP income specifically, this matters because MLP K-1s deliver a steady stream of ordinary income year after year. A $500,000 midstream portfolio yielding 7% distributes $35,000 annually, of which roughly 20-30% is currently-taxable income (the rest is return-of-capital that reduces basis). Call it $8,000-$10,000 of K-1 taxable income. At those levels, trust rates and MFJ 22-24% rates are roughly comparable.

The compression bites when K-1 income climbs higher — larger portfolios, or trusts that also hold other income-producing assets that push the aggregate past $15,650. For a trust with $30,000 of taxable income: trust tax is approximately $9,135 (30.5% effective). An MFJ couple in the 24% bracket would pay $7,200. That’s $1,935/year in compression cost — $19,350 over a decade.

Before diving into the IDGT and dynasty-trust analysis, set the baseline. Here’s the same 5-MLP portfolio in a revocable trust (Article 2’s territory) versus an irrevocable trust — computed side-by-side, 20-year horizon:

The irrevocable trust provides creditor protection and, for large estates, potential estate tax reduction. For MLP holders whose total estate is below the $15M exemption — which is most MLP holders — these benefits cost the full §1014 step-up (engine-computed at $39,406 federal + $84,000 §751 elimination for the canonical 5-MLP Y15 portfolio) and add 20 years of trust-rate compression, UBTI exposure, and admin overhead. Whether that trade-off is worth it depends on your estate size and creditor-risk profile — but now you know the exact price.

Note: IDGTs are irrevocable but taxed at grantor rates during life — the income-tax cost is shifted to the grantor, not imposed at compressed rates. The cost comes at death, when the IDGT may lose step-up. Non-grantor irrevocable trusts face both the compressed rates annually AND (potentially) the lost step-up. IDGT and non-grantor trusts have different problems — both covered below.

This is the most expensive trap in MLP estate planning, and it’s entirely avoidable with proper planning.

What an IDGT is

An Intentionally Defective Grantor Trust is designed to be “defective” for income tax purposes (income flows to the grantor’s personal return) but effective for estate tax purposes (assets are outside the gross estate). This is a feature, not a bug — it lets the grantor pay the trust’s income tax, effectively making an annual tax-free gift to the trust beneficiaries.

Why IDGTs work for most assets

The grantor pays income tax on trust income, assets grow inside the trust estate-tax-free, and at the grantor’s death the assets pass to beneficiaries without estate tax. For growth stocks with significant appreciation, this is a good deal — the estate tax savings at 40% outweigh the capital gains tax the beneficiaries will eventually pay at 15-20%.

Why IDGTs fail for MLPs

Because the IDGT assets are OUTSIDE the gross estate (that’s the entire point), they may NOT receive §1014 step-up at the grantor’s death. For MLPs, this means:

• All accumulated basis erosion survives — beneficiaries inherit the grantor’s near-zero basis
• All accumulated §751 recapture survives — beneficiaries face ordinary income on sale (not capital gains)
• The deferred tax liability that §1014 would have eliminated passes to the next generation unreset

The crossover computation

The IDGT saves estate tax (if the estate exceeds $15M) but costs the step-up. At what estate size does estate tax savings exceed lost step-up? Run the slider:

For estates UNDER the $15M exemption — which is most MLP holders — the IDGT provides zero estate tax savings but costs the full §1014 step-up. On the MLP portion of the estate specifically, the IDGT is pure loss.

For estates above the exemption, the crossover depends on how much of the estate is MLPs and how much has eroded to low basis. The step-up cost on a long-held midstream MLP position sitting at basis ~$0 is roughly 24% of FMV (engine-derived: LTCG + NIIT + §751 ordinary-income spread). The estate tax saving is 40% of the portion above the exemption. So on the MLP value alone, the IDGT wins once the MLPs sit fully above the exemption.

This may be the single most actionable paragraph in the entire estate-planning cluster.

Many IDGTs include a provision under IRC §675(4) — the “swap power” — that allows the grantor to substitute assets of equivalent value in and out of the trust. This provision is what makes the trust “intentionally defective” for income tax purposes. It’s included in most standard IDGT documents. And it’s the escape hatch for MLPs.

What the swap means for your MLPs

You hold 1,000 EPD units inside your IDGT. Current market value: $37,500. You also hold $37,500 in Treasury bonds in your personal taxable brokerage account.

You instruct the trustee to swap: EPD units come OUT of the IDGT into your taxable account. Treasury bonds go INTO the IDGT. The trust’s total value doesn’t change — equal-value exchange.

Phone script for your estate attorney

Phone script for the trustee

What if the IDGT doesn’t have a swap power?

Options narrow but don’t disappear: trust decanting (available in roughly 40 states), trust modification through court petition, or distribution to beneficiaries if trust terms permit. Consult an attorney. But check the trust document first — most IDGT attorneys include §675(4) by default.

This is the worked example nobody else will write because it’s too detailed. That’s the point.

John and Mary set up an IDGT in 2010. They transferred 2,000 EPD units at $25/unit ($50,000 total basis). John is the grantor. The trust benefits their two children. For 16 years, the IDGT “worked” exactly as designed: John paid income tax on the K-1 at his personal rate (because it’s a grantor trust), the assets grew outside the estate, distributions accumulated, and basis eroded toward zero.

For 16 years, the annual tax was identical to direct ownership. Because the IDGT is a grantor trust, the K-1 income flows to John’s personal return. The IDGT “worked” exactly as designed during life. The divergence happens at death.

John dies in 2026. Now the divergence.

Computation notes: sale gain $75,000 minus $44,000 §751 ordinary portion = $31,000 LTCG × 18.8% (LTCG + NIIT) = $5,828. §751 ordinary $44,000 × 32% bracket = $14,080. Total: $20,908. The IDGT saved $0 in estate tax (John’s total estate was under the exemption). It cost the children $20,908 in income tax they would have never owed under direct ownership. Sixteen years of identical tax treatment, followed by a single moment at death that cost everything §1014 was designed to prevent.

Most people think of UBTI as an annual nuisance — a few hundred dollars of business income triggering Form 990-T. The real UBTI danger for non-grantor trusts holding MLPs isn’t the annual income. It’s the sale.

When a trust sells MLP units, §751 recapture — accumulated over years or decades — is realized all at once. And it’s UBTI under §512. At compressed trust rates. In a single year.

For 2,000 EPD units held 15 years inside a non-grantor trust, the §751 time bomb is approximately $60,000 of accumulated ordinary income. Realized in one year at trust rates: roughly $21,500 in federal tax (after the $1,000 UBTI exemption), plus $500-1,500 in Form 990-T CPA costs — on a single position. The same position held directly in a taxable account and inherited at step-up would owe $0.

The word “time bomb” is not hyperbole. It’s a tax liability that grows silently every year the trust holds the MLP positions, and it detonates in full at the moment of sale.

The IRA UBTI issue is well-known. Most financial advisors reflexively say “don’t hold MLPs in an IRA.” The irrevocable trust UBTI issue is the same problem, with the same mechanics, but almost nobody warns you about it:

See MLPs in an IRA: UBTI Explained for the IRA side of this mechanics. The trust side works identically — the rules just live further from daily advisor conversation.

Same portfolio. Same distributions. Same market growth. The only thing that differs is the tax rate. Here’s the compounding gap on a $500,000 MLP portfolio generating $20,000 of taxable K-1 income annually:

Over 20 years on this illustrative portfolio, the non-grantor trust structure costs the beneficiaries approximately $92,000 in cumulative federal income tax and admin overhead — before accounting for UBTI on §751 recapture at eventual sale, and before any lost §1014 step-up.

Before the 2012 portability rules, estate attorneys routinely created credit shelter trusts (also called bypass trusts or B trusts) to use both spouses’ estate tax exemptions. At the first spouse’s death, assets up to the exemption amount went into an irrevocable bypass trust. This was standard planning for decades.

The problem: many of these trusts still hold MLP positions from 15-20 years ago. The MLPs have been sitting in the trust at compressed rates, generating K-1 complexity, and the trust beneficiaries (often the surviving spouse) have been paying more tax than necessary.

Why this matters now

• The 2012 portability election made bypass trusts largely unnecessary for estate tax purposes — the surviving spouse can use both exemptions without a trust
• But existing bypass trusts can’t be easily unwound — they’re irrevocable
• MLPs inside these trusts have been eroding basis at trust rates for years
• The surviving spouse may not even know the trust structure is costing them money

Options for MLPs in existing bypass trusts

1. Distribute MLP income using §663(b) — pull income out of trust rates to beneficiary rates annually
2. Distribute MLP units in-kind if trust terms permit — moves K-1 reporting to individual rates
3. Sell the MLPs inside the trust — triggers §751 recapture at trust rates, but may still beat ongoing compression if held many more years
4. Trust decanting — if your state allows it, move assets to a new trust with more favorable terms
5. Trust modification — petition the court to modify the trust to allow distribution of the MLP positions

If you’re a surviving spouse with MLPs in a bypass trust created before 2012, talk to an estate attorney about whether the trust structure still serves its original purpose. With portability now available, the trust may be creating cost without providing benefit.

Dynasty trusts (also called perpetual trusts, available in states that have abolished the Rule Against Perpetuities) are designed to hold assets for multiple generations — sometimes indefinitely. They’re popular for family wealth preservation.

MLPs inside a dynasty trust face a permanent problem: trust-rate compression applies for the life of the trust. There’s no “wait for death and step up” — the trust doesn’t die. The compressed rates are perpetual.

The generational cost

Compare cumulative trust-rate compression cost over 30, 50, and 100 years versus direct individual ownership with generational §1014 step-ups every ~30 years. Using the illustrative $11,000/year trust cost from Section 5 vs. $6,400/year individual cost, plus periodic §1014 resets that zero-out accumulated deferred tax:

Over 100 years, the dynasty trust structure costs approximately $460,000 more than direct ownership with generational §1014 step-ups on the same MLP positions. This is before accounting for §751 time-bomb sales inside the trust, state trust income tax, or cumulative 990-T admin costs.

Situation 1 — MLPs in an IDGT (step-up at risk)

• First: check for §675(4) swap power — if it exists, swap MLPs out TODAY (see Section 3b)
• If no swap power: evaluate whether the IDGT is actually saving estate tax (estate under exemption = no savings)
• If no savings and no swap: explore trust decanting or modification
• If estate is above exemption: the IDGT may still be the right structure — but quantify the step-up cost using the crossover calculator above

Situation 2 — MLPs in a bypass / credit shelter trust (pre-2012)

• Evaluate whether portability makes the bypass trust unnecessary
• Use §663(b) 65-day election to distribute income at individual rates — every year, not just once
• Consider distributing MLP units in-kind if trust terms permit
• Consider selective liquidation — sell MLPs inside the trust (triggering §751 at trust rates once) and reinvest in non-K-1 assets. The §751 hit hurts once; the compression bleeds forever.

Situation 3 — MLPs in a dynasty trust

• Use §663(b) aggressively to pull income out of trust rates annually
• Check whether the trust terms allow distribution of specific assets (MLP units) while retaining others
• Liquidate the most complex MLPs first (ET: 3 K-1 entities, 40+ states) and keep only the simplest
• If the trust must hold MLPs indefinitely: the Annual Cost Certificate below quantifies what that decision costs

Situation 4 — You’re planning a new irrevocable trust and considering adding MLPs

• Don’t. Hold MLPs directly in a taxable account for maximum §1014 step-up benefit.
• If you must use a trust: use a grantor trust that will be included in the gross estate (preserving step-up) — essentially a revocable trust, not an IDGT
• If the trust must be truly irrevocable: exclude MLPs from trust assets. Transfer stocks, real estate, and cash — keep MLPs out.

The 3 Phone Calls — Scripts for Taking Action

Annual Cost Certificate — print this

Attorney questions checklist

If your irrevocable trust holds MLPs AND is domiciled in a state with trust income tax, you’re paying state tax on the trust income on top of the compressed federal rates. For a trust in California holding 5 MLPs, the combined federal + state trust tax rate approaches 50%.

*Delaware taxes trust income only if beneficiaries are Delaware residents. Rates shown are top marginal rates — most states use graduated brackets.

If the trust document permits it, changing the trust’s situs to a no-income-tax state (Delaware, Nevada, South Dakota) can eliminate the state layer entirely. This requires appointing a trustee in the new state and meeting that state’s nexus requirements. Consult an attorney — but the savings can be thousands per year.

If you’re drafting a trust for a client who holds direct MLP positions, here’s what you need to know that may not be in your standard estate planning playbook:

1. MLP distributions reduce cost basis over time. After 10-15 years, the client’s broker may show a cost basis of $37,500 while the IRS-adjusted basis is near $0. The §1014 step-up at death eliminates this entire gap. Any trust structure that prevents step-up costs the beneficiaries the full amount of accumulated basis erosion.
2. §751 recapture is ordinary income, not capital gains. When MLP units are sold (or when step-up is lost), the §751 component is taxed at ordinary rates. For long-held positions, this can be $30,000-50,000+ per position. §1014 step-up eliminates this entirely. An IDGT does not.
3. Trust-rate compression is uniquely punitive for MLP income. Unlike capital gains from growth stocks (which may be minimal until sale), MLPs generate ongoing K-1 income every year. At compressed trust rates, this income is taxed at 37% starting at$15,650 — year after year.
4. The §675(4) swap power is your client’s escape hatch. Include it in every IDGT. It’s standard drafting. It lets you fix the MLP problem later without decanting or court modification.

For MLP-holding clients, the default should be direct ownership in a taxable account (or a revocable trust), with irrevocable structures used only when the estate tax math specifically justifies the income tax cost. Don’t let a standard estate planning template sweep MLPs into an IDGT by default.

Coming soon: International irrevocable trusts holding US MLPs — §1446 withholding, treaty implications, and the foreign trust reporting requirements (Form 3520, Form 3520-A) that most advisors overlook.