Master Limited Partnerships Explained: How MLPs Let Accredited Investors Access Energy Infrastructure Cash Flow

TL;DR: A master limited partnership (MLP) is a publicly traded partnership that combines stock-market liquidity with partnership tax advantages. Income passes through directly to you as a limited partner (LP) rather than being taxed at the entity level first, so MLPs often distribute more cash than comparable corporations. Most qualify under Internal Revenue Code Section 7704, which requires that at least 90% of gross income come from qualifying sources such as natural resource transportation and processing. If you are an accredited investor seeking energy infrastructure cash flow, MLPs deserve a close look — but the K-1 complexity and the IRA tax trap are real, and you need to understand both before buying a single unit.

What an MLP Actually Is and How It Is Built

An MLP is a publicly traded limited partnership. You buy "units" on a stock exchange like any stock, but you own a proportional interest in a partnership rather than equity in a corporation. That distinction drives everything about how MLPs are taxed, governed, and distributed.

The structure has two classes of owners. The general partner (GP), typically a corporation controlled by a large energy company sponsor, manages day-to-day operations and holds a small ownership stake, often around 2%. The limited partners (LPs), meaning the public unitholders, provide most of the capital and bear most of the economic risk but have no management role. Their liability is limited to their investment amount.

Historically, GPs held incentive distribution rights (IDRs), a contractual entitlement to a rising share of each marginal distribution dollar as the MLP hit higher payout thresholds. IDRs aligned GP and LP interests in theory but became expensive at scale, effectively taxing LP cash flows in favor of the sponsor. Between roughly 2016 and 2020, most large MLPs bought out or eliminated IDRs, reducing the cost of capital and simplifying distributions. Always check whether IDRs still exist before assuming you receive a clean share of distributable cash flow.

Distributions are paid quarterly. MLP partnership agreements typically specify a minimum quarterly distribution and management is contractually held to it, making distributions more predictable than corporate dividends, though still not guaranteed.

The Section 7704 Qualifying Income Test: Why Energy MLPs Are So Common

Congress enacted Section 7704 of the Internal Revenue Code in 1987 as part of the Omnibus Budget Reconciliation Act. The statute imposes a simple rule: if a partnership is publicly traded, it will be taxed as a corporation unless at least 90% of its gross income consists of "qualifying income."

What counts as qualifying income? The statute is specific. Under IRS final regulations issued in 2017 (TD 9817), qualifying income includes income and gains from the exploration, development, mining or production, processing, refining, transportation (explicitly including pipelines transporting gas, oil, or products thereof), and marketing of any mineral or natural resource. It also includes interest, dividends, real property rents, and gains from the sale of real property. It does not include income from general manufacturing, retail operations, or technology services.

This is why you almost never see a technology MLP or a manufacturing MLP. An MLP that drifted into non-qualifying income could lose its pass-through status and owe corporate income tax on all earnings, destroying the economic rationale for the structure. Management teams monitor the 90% threshold carefully, which is why midstream pipeline and storage assets make up the overwhelming majority of publicly traded MLPs today.

K-1 Tax Mechanics: What You Actually Have to Do at Tax Time

When you own MLP units, you do not receive a Form 1099-DIV. You receive a Schedule K-1 (Form 1065), the IRS form that partnerships use to allocate each partner's share of income, deductions, gains, losses, and credits. The IRS instructions for Form 1065 make clear that the partnership itself pays no income tax. Profits and losses pass through to partners, who report them on their own returns.

In practice, your K-1 arrives in mid-to-late March, after most brokerage 1099s, so plan for a later filing deadline. The K-1 reports several items that affect your taxes differently:

• Box 1 (ordinary business income or loss): MLPs hold depreciable pipeline and storage assets, so they typically show a net ordinary loss here, even when paying large distributions. That loss is passive and offsets only other passive income for most LP investors.
• Box 19A (cash distributions): Each distribution reduces your tax basis in the units rather than being taxable immediately. You pay no income tax on distributions as long as your basis stays above zero. This is the core tax advantage of MLP ownership.
• Section 751 recapture on sale: When you sell, accumulated depreciation converts to ordinary income. Your broker's cost basis is almost certainly wrong because it does not reflect K-1-adjusted basis. If you bought $8,000 in units and incurred $700 per year in net basis erosion for five years, your actual tax basis is roughly $4,500. Selling at "breakeven" price still creates a large taxable gain.

Filing complexity is real. Energy Transfer LP (ET) is structured as three separate entities, so unitholders receive three K-1 forms covering up to 44 states. MPLX LP (NYSE: MPLX) issues a single K-1, which is far simpler. Energy Transfer's investor relations page confirms that 2025 K-1 packages became available in March 2026 and include a state schedule for every jurisdiction where the partnership operates, adding a meaningful state tax filing burden.

The IRA Trap: UBTI and Why Retirement Accounts Are the Wrong Wrapper

Holding MLPs inside an IRA, Roth IRA, or 401(k) can result in your retirement account paying tax before a dollar reaches you. Tax-exempt entities are subject to a parallel tax on income unrelated to their exempt purpose. An IRA's purpose is retirement saving. Owning an operating business partnership falls outside that purpose. The IRS treats MLP operating income as unrelated business taxable income (UBTI). Fidelity's UBTI page states: "When an IRA is invested in an MLP or LP, it becomes a partner in the partnership. Becoming an owner of a business such as an MLP or LP is not considered within the exempt purpose of the IRA."

When total UBTI across all applicable investments in a retirement account reaches $1,000 or more in a tax year, your custodian must file Form 990-T and pay the resulting tax out of the account's cash balance. The tax is assessed at trust tax rates, which reach the top marginal federal bracket quickly on even modest income. That payment reduces account assets without appearing on a 1099-R.

Hold MLP units in a standard taxable brokerage account instead. If you want midstream exposure inside a retirement account, consider MLP-focused ETFs structured as C-corporations (such as AMLP) or midstream C-corps like Kinder Morgan (KMI). Those vehicles absorb corporate-level tax internally, which reduces yield but eliminates the UBTI risk entirely.

Real-World Examples: The MLPs You Will Actually Encounter

The MLP universe has consolidated since its peak around 2014-2015, when more than 100 publicly traded partnerships existed. Magellan Midstream Partners (MMP), one of the sector's benchmark names, was acquired by ONEOK in a $18.8 billion transaction that closed September 25, 2023, converting unitholders to ONEOK (OKE) shareholders. The names you are most likely to research today include:

• Enterprise Products Partners (EPD): One of the largest North American midstream MLPs, with more than 50,000 miles of pipelines and over 300 million barrels of storage capacity for NGLs, crude, and refined products. EPD declared $2.175 per unit in distributions for 2025, its 27th consecutive year of distribution growth, with distributable cash flow covering distributions 1.7 times according to fourth-quarter 2025 earnings reported in February 2026. The 1.7x coverage ratio indicates the partnership generates significantly more cash than it distributes, a key measure of distribution safety.
• Energy Transfer LP (ET): A large and complex midstream operator running natural gas pipelines, crude oil pipelines, NGL assets, and storage across 44 states. ET's multi-entity structure means three K-1 forms per year, a meaningful tax-filing burden. It has historically offered a higher yield than EPD, reflecting both higher leverage and the market's perception of somewhat higher risk.
• MPLX LP (MPLX): Formed by Marathon Petroleum (MPC), MPLX operates crude and refined product pipelines, terminals, gathering systems, and processing facilities primarily in the Appalachian and Permian basins. It issues a single K-1 and operates with a historically 8%-10% distribution yield, providing simpler tax reporting than ET. MPC's ownership stake aligns the general partner's interests directly with unitholders to a significant degree.

Distribution yield varies with unit price. When evaluating a potential investment, compare the yield against distributable cash flow (DCF) coverage, not just the headline percentage. An 8% yield with 1.3x coverage is meaningfully safer than an 8% yield with 0.9x coverage, where the partnership pays out more than it generates.

The Risks You Must Understand Before Buying

Commodity and volume risk: Even fee-based midstream MLPs have some exposure to commodity prices. When producers cut drilling in response to low prices, as happened in 2015-2016 and 2020, pipeline throughput declines and DCF can fall. Several MLPs cut distributions sharply during those periods.

Interest rate sensitivity: MLPs are high-yield income vehicles. Unit prices tend to fall when interest rates rise because competing fixed-income instruments become more attractive. You face both operating risk and rate risk simultaneously.

K-1 complexity and state filing costs: You may need to file state returns in every state where the MLP operates. Professional tax preparation for a multi-state K-1 can cost several hundred dollars annually, meaningfully eroding net yield on smaller positions.

Basis erosion and sale-year tax surprise: The pass-through tax benefits you enjoy while holding units create a deferred tax liability at sale. If you plan to hold for life and pass units to heirs, basis resets at death under current law and that liability disappears. If you plan to sell, model the tax consequences carefully before buying.

How to Evaluate an MLP Before You Invest

I look at four things when evaluating any MLP.

First, check distributable cash flow (DCF) coverage. I want at least 1.2x on a trailing twelve-month basis, ideally 1.5x or higher. Below 1.0x means the partnership funds distributions from debt or asset sales, which is not sustainable.

Second, examine the contract structure. Fee-based MLPs with take-or-pay contracts, where shippers pay whether or not they use the capacity, carry less commodity risk. Review the percentage of fee-based revenue in the annual 10-K on SEC EDGAR.

Third, check leverage. Debt-to-EBITDA above 4.5x is a yellow flag; above 5.5x warrants serious scrutiny. High leverage amplifies any volume or rate downturn.

Fourth, assess your tax situation first. If you cannot hold units in a taxable brokerage account, the tax benefits of MLP ownership largely disappear inside a retirement account. A midstream C-corp or a regulated ETF may serve you better at lower nominal yield but without the UBTI risk.

Frequently Asked Questions

Are MLP distributions the same as dividends?

No. MLP distributions reduce your cost basis rather than being taxed as dividend income. You owe no income tax on a distribution as long as your basis stays above zero, which creates tax deferral. When you sell, that deferral reverses as a taxable gain. Corporate dividends from midstream C-corps like Kinder Morgan are taxed in the year received at the 15% or 20% qualified rate for most investors.

Can I hold an MLP in my Roth IRA and avoid all taxes?

Not entirely. UBTI applies to Roth IRAs too. If the MLP generates more than $1,000 in UBTI in a given year, your custodian must file Form 990-T and pay tax from the account's cash balance. No 1099 is issued for that payment, but your balance shrinks. Small positions may stay under the threshold, but larger allocations or multiple MLP holdings increase the risk of crossing it.

What happens to my MLP units when I die?

Under current federal tax law, MLP units receive a stepped-up basis at death equal to fair market value on the date of death. All accumulated basis erosion from K-1 distributions and depreciation allocations disappears, making the tax deferral effectively permanent for long-term holders who pass units to heirs. Congress has periodically proposed limiting step-up in basis. Consult a tax advisor about the current status of this rule and your estate plan.

How do I get my K-1, and when does it arrive?

MLPs file Form 1065 with the IRS and issue K-1 forms to each unitholder, typically in mid-to-late March, later than standard brokerage 1099s. MPLX's 2025 K-1 packages were posted mid-March 2026. Energy Transfer's appeared online March 13, 2026. Do not file your tax return before all K-1s arrive or you will need an amended return. Most tax professionals recommend filing an extension (Form 4868) if you own MLP units, giving you until October 15 to finalize without penalty.

Author Disclosure: Jeff Barnes, MBA has no personal position in any company, fund, or platform named in this article. Angel Investors Network has no current commercial relationship with any party mentioned. AIN provides marketing and education services, not investment advice. Past performance does not guarantee future results. All investments involve risk, including loss of principal.