What Is a Master Limited Partnership (MLP)?

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A master limited partnership (MLP) is a business organized as a limited partnership whose ownership units trade on a public stock exchange. It combines the tax treatment of a partnership, where income is taxed only once at the owner level, with the liquidity of an exchange-listed security. In the United States, an MLP keeps that partnership status only if at least 90% of its gross income is “qualifying income,” a category that consists mostly of natural resource and real estate activity. That rule is why most MLPs own pipelines, storage terminals, processing plants and similar energy infrastructure.

How a Master Limited Partnership Works

An MLP trades like a corporation’s stock, but for tax purposes it is treated as the sum of its partners rather than as a separate taxpaying entity. It has two classes of owners.

• General partner (GP). The GP runs the partnership, makes operating and capital decisions, and is responsible for providing the services the business needs. An MLP technically may have no employees of its own; the people who operate its assets are often employed by the general partner or an affiliate. The GP’s economic stake has traditionally been small, around 2%, with the option to increase it. GPs are compensated based on how the partnership performs, and some structures have included incentive distribution rights that give the GP a growing share of cash as distributions rise.
• Limited partners (LPs). These are the public investors, who hold units and are called unitholders. They contribute capital, receive periodic cash distributions (typically quarterly), and are allocated a share of the partnership’s income, gains, losses, deductions and credits. They do not manage the business, and their liability for the partnership’s debts is limited to the capital they contributed.

The partnership agreement governs how cash moves. Many agreements call for distributing available cash to unitholders each quarter, after the partnership covers operating costs and the reserves the general partner sets aside. Because so much cash goes out, MLPs that want to build new assets typically fund growth by issuing new units or borrowing rather than relying mainly on retained earnings.

The structure suits capital-intensive businesses with predictable cash flows, such as a pipeline collecting fees under long-term contracts. Without corporate income tax, more cash is left to distribute or reinvest, which can lower the partnership’s cost of capital compared with a similar business organized as a corporation.

A brief history

The first MLP was organized in 1981. As businesses in many unrelated industries adopted the structure, Congress grew concerned about lost corporate tax revenue. Legislation in 1987 generally required publicly traded partnerships to be taxed as corporations unless they met the qualifying income test. That restriction still limits MLPs largely to natural resources, real estate and a few related categories.

How MLPs Are Taxed

Pass-through income

A corporation pays corporate income tax on its profits, and shareholders then pay personal tax on the dividends they receive. That is double taxation. An MLP skips the first layer. The partnership generally pays no federal income tax, and each unitholder reports an allocated share of the partnership’s income on a personal return, whether or not that income was distributed in cash.

Deductions pass through as well. Energy infrastructure carries heavy depreciation, and natural resource businesses may also claim depletion. These deductions flow to unitholders and offset the income allocated to them, which is why the taxable income on a unitholder’s return is often much smaller than the cash received.

Qualifying income

To keep pass-through treatment, at least 90% of an MLP’s gross income must come from qualifying sources. These include income from the exploration, development, production, processing, transportation, storage and marketing of minerals and natural resources such as oil and natural gas, along with real property rents, interest, dividends and gains from qualifying assets. A business that cannot meet the test is taxed as a corporation even if it is organized as a partnership.

Distributions and cost basis

MLP distributions look like dividends, since cash arrives quarterly, but they are taxed differently. The part of a distribution that exceeds the unitholder’s allocated taxable income is generally a return of capital. It is not taxed when received. Instead, it reduces the unitholder’s cost basis in the units.

Basis moves in both directions each year:

Adjusted basis = original cost + allocated income − allocated losses and deductions − cash distributions

When basis reaches zero, further distributions are taxed as capital gains in the year received.

What happens at sale

The deferral ends when units are sold. The gain equals the sale price minus the adjusted basis, so years of basis reductions increase the gain. That gain is split into two parts:

1. Ordinary income (recapture). The portion tied to the depreciation and similar deductions previously passed through to the unitholder is taxed at ordinary income rates.
2. Capital gain. The remainder, roughly the appreciation in the units, is taxed as a capital gain, at long-term rates if the units were held for more than a year.

Other tax features

• Qualified business income deduction. Under Section 199A, individuals can generally deduct up to 20% of their qualified publicly traded partnership income. The deduction applies to the qualifying income allocated to the unitholder, not to the cash distributions themselves.
• Inheritance. Units passed to heirs at death receive a step-up in basis to fair market value on the date of death, which can eliminate the deferred tax built up through return-of-capital distributions. Units given as a gift do not get a step-up; the recipient generally takes over the donor’s basis.

Example of a Master Limited Partnership Investment

In a hypothetical example with figures not drawn from any real partnership, an investor buys 100 units at $20, for an original basis of $2,000. Assume:

• The MLP pays $0.50 per unit per quarter, or $200 per year.
• Each year the K-1 allocates $40 of net taxable income to the investor after depreciation and other deductions.
• The investor holds the units for five years, then sells them at $22 per unit.

Tax while holding. Each year the investor reports $40 of income, although $200 in cash was received. The other $160 is treated as a return of capital.

Basis after five years. $2,000 + (5 × $40) − (5 × $200) = $2,000 + $200 − $1,000 = $1,200.

Gain at sale. $2,200 sale proceeds − $1,200 adjusted basis = $1,000.

Only $200 of that gain comes from the units rising from $20 to $22. The other $800 comes from basis reductions, meaning cash the investor received earlier without paying current tax. Assume the partnership’s sale information attributes $750 of the gain to recapture of previously passed-through deductions. That $750 is taxed as ordinary income, and the remaining $250 is a long-term capital gain.

Over five years, the investor collected $1,000 in cash and reported only $200 of taxable income. The rest was deferred until the sale, when a large share of it was taxed at ordinary rates. Because a tax paid in year five costs less than the same tax paid today, the deferral has value in net present value terms.

Why Companies and Investors Use MLPs

For sponsors. Many oil and gas companies have used MLPs to hold stable, fee-based assets. Selling units lets the sponsor raise capital from public investors while keeping control through the general partner interest. Some corporations hold large unit positions in their own MLPs, and some have created separate publicly traded corporations whose main asset is MLP units, so investors who want a 1099 and ordinary dividends can still get exposure.

For investors. The attractions are mostly about income:

• Cash yield. Because MLPs distribute much of their cash, their yields have historically tended to be higher than the average dividend yield on stocks.
• Tax deferral. Return-of-capital treatment shelters much of the current cash from current tax.
• Liquidity. Unlike interests in private partnerships, MLP units can be sold on any trading day.
• Contracted revenue. Infrastructure MLPs often earn fees under long-term service contracts, which can make cash flow steadier than in businesses tied directly to commodity prices.

Most MLPs operate in energy. Typical activities include running crude oil, refined product and natural gas pipelines; gathering and processing natural gas; storage and terminals; refinery services; and supply and logistics support for producers. Some MLPs explore for and produce oil and gas directly, which exposes them more to commodity prices than fee-based pipeline operators. The Alerian MLP Index is a widely followed benchmark for energy infrastructure MLPs.

When valuing an MLP, analysts often focus on distributable cash flow, distribution coverage (how many times that cash flow covers the distribution) and leverage. Earnings per share is less useful because large depreciation charges depress reported net income. Cash-flow approaches such as discounted cash flow and debt-inclusive measures such as enterprise value fit the structure better.

Limitations of a Master Limited Partnership

• Schedule K-1 reporting. Unitholders receive a Schedule K-1 each year instead of a Form 1099. K-1s can be complex and may arrive later than other tax forms, which can delay filing or increase preparation costs.
• State tax filings. Unitholders may owe tax, and have to file returns, in each state where the partnership earns income. A pipeline that crosses several states can create several filing obligations, although small allocations may fall below a state’s filing threshold.
• Loss limitations. Losses passed through from an MLP are passive and generally can offset only future income from the same partnership. They cannot offset wages or other investment income. Unused losses carry forward and are released when the investor sells the entire position.
• Retirement accounts. Income from an MLP held in an IRA or other tax-exempt account can be unrelated business taxable income (UBTI). If an account’s UBTI exceeds $1,000 in a year, the account itself may owe tax and must file a return. The account also gains little from the MLP’s deferral, since the account is already tax-advantaged.
• Sector concentration. A portfolio of energy MLPs is a concentrated bet on one industry, its regulation and the volumes moving through its assets.
• Limited growth from retained cash. Expansion depends on access to debt and equity markets, and unit appreciation tends to be modest compared with companies that reinvest their earnings.
• Distribution risk. Distributions are set by the partnership, not guaranteed. They can be reduced or suspended if cash flow drops or leverage becomes too high, and the units can fall in price at the same time.
• Governance. Limited partners usually have fewer voting rights than corporate shareholders, and the general partner’s interests can differ from theirs, particularly where the GP is paid through incentive distribution rights.

MLP vs. Stock and Other Structures

MLP units vs. common stock. Stockholders own shares in a corporation that pays corporate income tax; dividends are taxed again when received and reported on a Form 1099. MLP unitholders are partners: they are taxed on their allocated share of income, whether or not it was distributed, receive a K-1, and adjust their basis every year. Corporate dividends do not reduce a shareholder’s basis, while MLP return-of-capital distributions do.

MLP vs. LLC. A limited liability company is a state-law business entity that is often taxed as a partnership, but most LLCs are privately held. Some MLPs are actually organized as LLCs. What makes an entity a master limited partnership is public trading combined with partnership tax treatment, not the specific legal form.

MLP vs. REIT. A real estate investment trust is a corporation that avoids entity-level tax mainly by distributing most of its taxable income. REIT investors receive a 1099, and dividends are mostly taxed as ordinary income in the year received. MLPs pass income through instead, and their distributions are often largely tax-deferred.

MLP vs. MLP funds. Mutual funds and ETFs that hold MLPs give investors a 1099 instead of a K-1. However, a fund that invests heavily in MLPs is often organized as a corporation and pays corporate tax itself, which reduces returns compared with holding the units directly. Exchange-traded notes linked to MLP indexes avoid that entity-level tax but carry the credit risk of the issuing bank.

The Bottom Line

MLPs matter most to income investors in taxable accounts who can handle Schedule K-1 reporting and possible state filings. The structure delivers high cash yields with much of the tax deferred, but that deferral reverses at sale, when recapture is taxed at ordinary rates. Investors also face concentration in energy, distributions that are not guaranteed, and limited voting rights, while MLP funds simplify reporting at the cost of corporate tax.