Does MPLX issue a K-1?

Yes. MPLX LP is a publicly traded partnership. Every unitholder receives a Schedule K-1 (Form 1065) annually. Unlike Energy Transfer (3 K-1s), MPLX issues a single K-1 per tax year.

When is the MPLX K-1 available for the 2025 tax year?

MPLX typically posts K-1s in mid-March. In 2025, K-1s were available March 14. The 2025 K-1 is expected by mid-March 2026 at taxpackagesupport.com/mplxlp. Phone: 800-232-0011.

What is the difference between MPC and MPLX for taxes?

Marathon Petroleum (MPC) is a C-corporation — dividends arrive on a 1099-DIV and are taxed at qualified dividend rates. MPLX is a partnership — distributions arrive on a K-1, reduce your cost basis, and eventually trigger §751 ordinary income recapture when you sell.

How fast does MPLX erode my cost basis?

At an 8–10% distribution yield, expect roughly 5–8% annual net basis erosion after K-1 income offset. After 5 years, your IRS-adjusted basis can be 30–40% below what your broker shows.

What is §751 recapture on MPLX?

When you sell MPLX units, cumulative depreciation passed through on prior K-1s is recaptured as ordinary income under §751, taxed at up to 37% — not capital gains rates. The amount appears on the Sales Schedule in your final K-1.

Which states require tax filing for MPLX unitholders?

MPLX operates in Appalachian Basin (PA, WV, OH), Permian Basin (TX, NM), and Gulf Coast states. Texas has no income tax. Most small unitholders file in their home state plus 0–2 additional states. Sale year expands obligations significantly.

What happens if I confuse MPC dividends with MPLX K-1 distributions?

Marathon Petroleum (MPC) is a C-corporation that issues a 1099-DIV with qualified dividends. MPLX is a partnership that issues a K-1 with distributions that reduce your cost basis. If you own both, you have two completely separate tax workflows. Do not enter MPC dividend information on your MPLX K-1 or vice versa.

Can I sell MPLX at my purchase price and owe no tax?

No. Selling at your original purchase price does not mean zero tax. Your IRS-adjusted basis is lower than your purchase price due to years of K-1 distribution erosion. The difference between your sale price and your K-1-adjusted basis is your taxable gain, and part of it is section 751 ordinary income.

What happens if I don't check the PTP box in TurboTax for my MPLX K-1?

TurboTax will treat the K-1 as a general partnership instead of a publicly traded partnership. This changes how losses are handled under passive activity rules, may affect your section 199A QBI deduction, and can cause errors when you sell. Always check "Publicly Traded Partnership" for MPLX.

Where do I find the section 199A QBI information on my MPLX K-1?

The section 199A QBI data is reported in Box 20 Codes Z and AE, but the actual amounts are on the supplemental statement attached to your K-1 — not in Box 20 itself. If you only look at the main K-1 form, you will miss the QBI deduction entirely.

Do I need to track liability changes (Item K) on my MPLX K-1?

Yes. Item K at the bottom of K-1 page 1 shows your share of partnership liabilities. Increases add to your basis, decreases reduce it. Ignoring Item K means your basis calculation is wrong, which affects your taxable gain when you sell.

What happens if I use my broker's cost basis when selling MPLX?

Your broker reports your original purchase price, but the IRS expects your K-1-adjusted basis which decreases each year from distributions and other K-1 items. Using the wrong basis underreports your gain and can trigger an IRS CP2000 notice with back taxes, interest, and possible penalties.

MPLX K-1 Guide

Yes, MPLX issues a K-1 — one per year, one entity, simpler than ET. But its 8–10% yield erodes your tax basis fast. After 5 years, your IRS basis could be 30–40% below what your broker shows — and that gap becomes a taxable surprise when you sell.

By Lucas Andersen — Last updated March 6, 2026

Track your MPLX basis automatically: K-1 Basis Tracker — upload your K-1 PDF or enter boxes manually. Free IRS worksheet, basis history chart, and export.

2025 K-1 Release Date

MPLX typically makes K-1s available in mid-March. In 2025, K-1s were posted March 14. The 2025 K-1 is expected by mid-March 2026. Access at taxpackagesupport.com/mplxlp or call 800-232-0011.

What Is MPLX LP?

MPLX LP is a large-cap midstream MLP formed by Marathon Petroleum (MPC). Two segments: Logistics & Storage (crude/refined products pipelines, terminals) and Gathering & Processing (natural gas systems in Appalachian Basin and Permian Basin). Single PTP entity — one K-1, simpler than ET’s three-entity structure. Historically 8–10% distribution yield with 1.5x+ coverage.

MPLX and Marathon Petroleum (MPC): The Corporate/MLP Distinction

Marathon Petroleum Corporation (MPC) is MPLX’s general partner and majority unitholder. MPC is a C-corp — you get a 1099-DIV. MPLX is a partnership — you get a K-1. Owning both means two different tax workflows. MPC dividends are qualified (taxed at 15–20%), while MPLX distributions reduce basis and eventually trigger §751 recapture at sale. If you hold both, do not confuse MPC’s 1099-DIV with MPLX’s K-1 — they are separate securities with entirely different tax treatment. Similar corporate/MLP pairs include PAA and CQP.

High Yield Means Faster Basis Erosion

MPLX’s 8–10% yield means roughly 5–8% annual basis erosion after K-1 income offset. Example: 250 units at $40 ($10,000). After 5 years of ~$700/year net erosion, basis drops to ~$6,500 — a 35% gap. Broker still shows $10,000. Selling at “breakeven” on price creates a $3,500 taxable gain, part of which is §751 ordinary income.

K-1 Box Walkthrough

Box 1: ordinary income/loss (usually net loss from depreciation). Box 19A: cash distributions (reduces basis). Item K: liability share (increases/decreases basis). Box 20 Code Z: §199A QBI data on supplemental statement. Box 20 Code AH: §751 gain (sale year only). For a full walkthrough of each line, see the K-1 Basis Worksheet Explained.

MPLX vs ET Comparison

MPLX: 1 K-1, 1 basis calculation, 1 passive activity, ~15–20 states, 1 disposition. ET: 3 K-1s, 3 basis calculations, 3 passive activities, ~44 states, 3 simultaneous dispositions. MPLX is significantly simpler, though the same IRS basis rules apply.

State Filing

MPLX operates in Appalachian Basin (PA, WV, OH), Permian Basin (TX, NM), and Gulf Coast. Texas has no income tax. PA and WV have low thresholds. Most investors file in home state plus 0–2 additional states. Sale year expands filing significantly. For thresholds and composite return details, see MLP State Filing Requirements.

Common MPLX K-1 Mistakes

Confusing MPC (1099-DIV) with MPLX (K-1) — different securities, different tax treatment
Assuming “breakeven” price means no tax owed
Not checking “Publicly Traded Partnership” in TurboTax
Missing the §199A supplemental statement (not in Box 20 itself)
Ignoring liability changes (Item K)
Using broker basis instead of K-1-adjusted basis when selling