For years, cannabis businesses paid tax like no one else in America. They could owe federal income tax on money they never really kept, all because of one short provision in the tax code. In 2026, that provision finally started to crack.
If you advise cannabis clients or run a shop yourself, this is the part of the law that has shaped your numbers more than any other. Here is what it does, why it hurt so much, and what the recent move on medical cannabis actually changes.
Section 280E of the Internal Revenue Code is short, but it carries enormous weight. Written into law back in 1982, it says a business cannot take deductions or credits if that trade or business consists of trafficking in controlled substances under Schedule I and II of the Controlled Substances Act (CSA).
The formal citation is Internal Revenue Code Section 280E, codified at 26 U.S.C., and most tax pros just call it the Code § 280E problem or cite the IRC. The point is simple. If the federal government treats your product as a Schedule I substance, the law will not let you write off normal costs. Cannabis sat on Schedule I for decades, so every state-legal cannabis seller fell inside this rule, even when fully licensed under state law.
The original logic was about drug enforcement. Lawmakers did not want to hand tax breaks to activity that was prohibited by federal law, and the statute was aimed squarely at trafficking. Cannabis, caught by the same Schedule I label, came along for the ride.
Here is where it stings. A normal company subtracts its everyday costs before paying tax. Rent, wages, marketing, all of it lowers taxable income. The statute takes that away from cannabis operators.
So a dispensary could not deduct rent. A cultivator could not claim payroll or advertising. For a cannabis seller, deducting ordinary and necessary business expenses simply was not allowed, even though every other small business writes them off freely. The result was a brutal federal tax burden, with some operators facing effective tax rates far above what their real profit could support.
The provision works as a flat bar to claiming deductions tied to the plant. It does not care that you follow every state rule to the letter. As long as cannabis stayed on Schedule I, the answer on those write-offs was no.
There was always one exception, and cannabis accountants built whole strategies around it. The rule blocks write-offs, but it cannot touch cost of goods sold.
Why? Because COGS is not technically a write-off. It is a subtraction used to figure gross income in the first place. Courts have long held that the government can tax income, but product cost comes out before you even reach income, so it stays deductible. For a shop, that meant the wholesale cost of the product itself could lower the bill, while almost everything else could not.
It helped, but only so far. Two stores with identical sales could owe wildly different tax depending on how much of their spending counted as product cost versus ordinary business expenses. That gap is exactly why cannabis tax planning became its own little industry.
For a long time the only real fix was to reschedule the drug itself. In 2026, that started to happen.
It began with an executive order. On December 18, 2025, President Trump directed the Justice Department to finish the job as quickly as the law allowed. The DOJ moved fast. In April 2026 it issued a final order rescheduling marijuana from Schedule I to Schedule III for two narrow groups. The first is cannabis sold under a state medical marijuana license, and the second is FDA-approved products containing cannabis. The effective date was the publication in the Federal Register on April 28, 2026.
This matters because 280E only reaches Schedule I or II controlled substances. Once state-licensed medical marijuana became a Schedule III item rather than a Schedule I drug, the statute stopped applying to it. Those operators can now deduct the everyday costs they were denied for years. Treasury and the IRS have said guidance is coming on the details, including a transition rule that generally treats the change as applying for the full taxable year that includes the effective date.
One big caution. This shift covers medical marijuana only. Recreational, or adult-use, cannabis is still on Schedule I, so the rule still applies there in full. A broader review of all cannabis is underway, with a DEA hearing set to begin June 29, 2026, that could eventually move the rest. None of it is locked in, since a court decision or fresh legal challenge could still reshape the timeline.
So where does this leave the people actually running the business?
If you operate on the medical side under a state license, the change is real money. You may be able to file amended returns for open years and claim costs you could not before, and the Internal Revenue Service has signaled it will spell out how far back that retrospective relief can go. Shops that sell both medical and recreational product will need to apportion their spending carefully once that guidance lands, because the disallowance still shadows the recreational half.
For advisers, this is the moment to revisit every cannabis client's position. The tax implications run from prior-year amended returns to how you structure entities going forward. The rules are moving quickly, and a single court ruling could shift them again, so the safe play is to document positions well and watch for fresh agency guidance rather than assume today's setup is permanent.
Cannabis returns were always detailed, and the 2026 changes made them more so. Sorting which costs belong in COGS, rebuilding prior years for amended filings, splitting expenses for mixed operators, and keeping federal and state treatment straight is a lot of careful work for a CPA firm with cannabis clients on its roster.
This is where Madras Accountancy supports U.S. CPA firms. We handle the tax preparation groundwork behind cannabis returns, from cost allocations and reconciliations to the prior-year analysis these new rules invite, all under your firm's review and your firm's name. If cannabis files are stretching your team, it is worth a conversation.
What is the 280E rule? It is a provision in the federal tax law that denies income tax deductions and credits to any business trafficking in a Schedule I or II substance. Because cannabis was a Schedule I drug, sellers could not write off normal operating costs.
Why could cannabis businesses not deduct expenses? Because the statute treats the entire operation as drug trafficking under federal rules. That label blocked the everyday write-offs, like rent and payroll, that ordinary companies use to lower their own income.
Can a cannabis business still subtract cost of goods sold? Yes. COGS was never blocked, because it reduces gross income rather than counting as a deduction. That is why product cost stayed claimable even when everything else did not.
Did the 2026 rescheduling end 280E for everyone? No. The April 2026 order moved only state-licensed medical cannabis and FDA-approved products to Schedule III. Those medical operators are now free of the rule, but the change did not reach the whole market.
Does the rule still apply to recreational cannabis? Yes. Adult-use cannabis remains on Schedule I federally, so the deduction bar still applies to recreational operators in full while the broader review continues.
When did the change take effect? The effective date was April 28, 2026, the day the order was published in the Federal Register. Guidance from Treasury points to the relief generally applying for the full tax year that includes that date.
Can medical operators recover tax from past years? Possibly. The order encouraged the agencies to consider retrospective relief, and operators may look at amended returns or protective claims for open years. The exact reach depends on guidance still being written.
Does the rule affect state tax returns too? It depends on the state. Several states decoupled from the federal rule years ago, letting licensed operators claim ordinary expenses on the state return even when the federal bar still applied.
This rule shaped cannabis finances for four decades, and 2026 is the first year that grip has loosened in a real way. Medical operators have room to breathe, recreational sellers are still waiting, and the guidance that fills in the gaps is only starting to arrive. Knowing exactly where a given client sits is what turns this shift into savings instead of risk. If your firm wants that work handled cleanly, Madras Accountancy is glad to help.
This article is general information for cannabis operators and their advisors, not formal tax advice. Federal cannabis rules are changing quickly, so confirm your specific situation with a qualified tax professional before acting.
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