Connecticut Replaces THC Potency Tax with 10.75% Excise Tax

On May 14, 2026, Governor Ned Lamont signed a state budget that included a provision cannabis operators and consumers have been pushing for since Connecticut's adult-use market launched: the elimination of the state's per-milligram THC potency tax and its replacement with a flat 10.75 percent excise tax on gross receipts, effective October 1, 2026.

The change may sound technical. It is not. This is one of the most consequential cannabis tax reforms enacted by any state this year, and it carries implications that extend well beyond Connecticut's borders. Here is what changed, why it matters, and what it signals about the direction of cannabis taxation nationally.

The old system: a per-milligram nightmare

Connecticut's original cannabis tax structure was built on a premise that sounded reasonable in theory but proved deeply problematic in practice: tax cannabis based on the amount of THC each product contains.

Under the old system, the state imposed a per-milligram tax on THC content that varied by product category.

Flower was taxed at $0.00625 per milligram of THC. For a gram of flower testing at 25 percent THC (250 milligrams), this worked out to roughly $1.56 in potency tax per gram, on top of the standard state sales tax.

Edibles were taxed at $0.0275 per milligram of THC. A standard 100-milligram edible package (ten servings at 10 milligrams each) carried a potency tax of $2.75.

Concentrates and vapes were taxed at $0.009 per milligram of THC. A one-gram vape cartridge testing at 80 percent THC (800 milligrams) was hit with $7.20 in potency tax.

The logic behind potency-based taxation was straightforward: products with more THC should bear more tax, similar to how alcohol excise taxes scale with proof. Public health advocates argued that this approach would discourage the production and consumption of high-potency products by making them disproportionately expensive.

In practice, the system created a cascade of problems that undermined both the industry's competitiveness and the state's revenue goals.

Why the potency tax failed

The per-milligram system failed for several interconnected reasons.

Administrative complexity. Calculating THC-based taxes required operators to track potency data for every product at every stage of the supply chain. Because THC content varies between batches — even batches from the same cultivar grown by the same operator — the tax liability for identical-looking products could differ significantly. Accounting systems had to integrate lab testing data with point-of-sale tax calculations in real time, creating compliance costs that fell disproportionately on smaller operators without sophisticated software infrastructure.

Testing variability. Cannabis potency testing is not perfectly precise. THC content can vary by several percentage points between tests of the same batch, and different testing laboratories may produce different results for identical samples. When tax liability is calculated on a per-milligram basis, testing variability translates directly into tax liability uncertainty — a problem that no other retail product category faces.

Competitive disadvantage. Connecticut's potency tax made its cannabis products more expensive than those in neighboring Massachusetts, which levies a flat 10.75 percent excise tax. For consumers near the state border — and in the northeastern United States, virtually everyone is near a state border — the price difference was a concrete incentive to drive to Massachusetts for their purchases. Connecticut was losing sales and tax revenue to a state that had adopted the simpler, more competitive tax model.

Disproportionate impact on concentrates. The per-milligram rate structure hit concentrates and vapes hardest because these products contain the highest THC concentrations per unit weight. A $7.20 potency tax on a one-gram vape cartridge represented a significant percentage of the retail price, particularly as wholesale prices for concentrates fell due to oversupply. Operators reported that the potency tax on concentrates was making entire product categories unviable in the Connecticut market.

Perverse incentives. Perhaps most counterintuitively, the potency tax created an incentive for operators to produce and sell products with lower tested THC content — but this did not necessarily mean less potent products. It meant products that tested lower on the specific day they were tested, introducing incentives around testing timing and methodology that served no public health purpose.

The new system: simplicity and alignment

The 10.75 percent excise tax on gross receipts replaces the entire per-milligram framework with a single, straightforward calculation. Whatever the retail price of a cannabis product, 10.75 percent of that price goes to the state as excise tax. No milligram calculations. No product-category differentials. No integration of lab testing data into tax computation.

The rate is not arbitrary. It matches Massachusetts's cannabis excise tax rate exactly, which was plainly intentional. By aligning with its most significant competitor, Connecticut eliminates the cross-border price disadvantage that the potency tax created. Consumers who previously drove to Massachusetts to save money on cannabis will find Connecticut's prices competitive when the new rate takes effect on October 1.

The simplicity of the new system also dramatically reduces compliance costs for operators. Point-of-sale tax calculations become identical to those for any other excise-taxed consumer product. The need to integrate potency testing data into tax accounting disappears. Smaller operators who lacked the resources to manage the per-milligram system's complexity will benefit disproportionately.

Industry reaction: 4/20 celebration was no accident

The timing of this reform is noteworthy. The legislation advanced through the Connecticut General Assembly in late April, and the cannabis industry celebrated its progress on 4/20 — a date whose symbolic significance was not lost on the operators, advocates, and lawmakers who had pushed for the change.

Industry reaction has been overwhelmingly positive. Operators describe the shift as the single most impactful regulatory change since Connecticut's adult-use market launched. The administrative burden reduction alone is significant, but the competitive realignment with Massachusetts is what operators emphasize most. Border-town dispensaries that had been losing foot traffic to Massachusetts retailers expect to see customers return.

Cannabis industry groups in Connecticut had been lobbying for this change for more than a year, arguing that the potency tax was suppressing market development at a critical stage. Connecticut's adult-use market is still young, and the tax structure in its early years has an outsized impact on whether the legal market can capture sales from the illicit market. High taxes — particularly complex, hard-to-predict taxes — drive price-sensitive consumers toward untaxed alternatives.

What this means for consumers

For Connecticut cannabis consumers, the practical impact will depend on what products you buy.

Flower prices should remain roughly similar. The per-milligram potency tax on flower was relatively modest, and the 10.75 percent excise tax will produce comparable tax liability at current retail price points. Consumers purchasing standard flower products may not notice a significant price change.

Concentrate and vape prices should decrease. These categories bore the heaviest potency-tax burden under the old system. The shift to a percentage-of-price excise tax will lower the effective tax rate on high-potency products, which should translate to lower retail prices for vape cartridges, dabs, and other concentrate formats.

Edible prices should see modest relief. Edibles occupied a middle ground under the potency tax, and the shift to 10.75 percent excise will provide some price reduction, though less dramatic than the concentrate category.

Overall market competitiveness improves. Even where individual product prices do not change dramatically, Connecticut's cannabis market becomes more competitive with Massachusetts. Consumers who had been crossing the border will find less incentive to do so, and the broader market development that results from keeping sales in-state should improve selection and accessibility over time.

The national context: how states are learning from each other

Connecticut's reform is part of a broader national trend in which states are revisiting their initial cannabis tax structures as the practical consequences of those designs become clear.

The cannabis tax landscape across legal states is remarkably varied. Some states use excise taxes on gross receipts. Others use ad valorem taxes at the wholesale level. Several have experimented with weight-based taxes, potency-based taxes, or hybrid structures that combine multiple approaches.

What is becoming increasingly clear as more data accumulates is that simplicity wins. States with straightforward excise tax structures tend to achieve better compliance rates, lower administrative costs, more competitive retail pricing, and ultimately higher tax revenues than states with complex, multi-variable tax frameworks.

Washington State learned this lesson after experimenting with a layered tax structure that combined excise and sales taxes at rates that initially pushed effective tax rates above 40 percent. The state eventually restructured to a 37 percent excise tax at the retail level — still high, but dramatically simpler than the original design.

Illinois's tax structure, which includes potency-based tiers, has faced similar criticism from operators who argue that the complexity suppresses market development. Colorado, one of the first states to legalize, has adjusted its tax rates multiple times as the market matured and the relationship between tax rates, legal market capture, and illicit market persistence became clearer.

Connecticut's move aligns the state with what is emerging as the consensus best practice: a flat excise tax at a rate competitive with neighboring jurisdictions, simple enough for operators to calculate and for consumers to understand.

What comes next

The October 1, 2026 effective date gives operators and the state's regulatory infrastructure several months to prepare for the transition. Point-of-sale systems will need to be updated, accounting practices adjusted, and pricing strategies recalibrated.

For the state government, the revenue implications will be closely watched. The potency tax generated revenue that the state has come to depend on, and the excise tax needs to produce comparable or greater revenue to be considered a success by budget planners. The expectation — supported by the experience of other states — is that the simpler, more competitive tax structure will expand the market's overall size sufficiently to offset any per-unit tax reduction.

For the broader national conversation about cannabis taxation, Connecticut's reform adds another data point to a growing body of evidence that complexity and high effective rates are counterproductive. States considering cannabis legalization should take note: the tax structure you choose at launch will shape your market for years, and the states that got it right chose simplicity.

Governor Lamont's signature on May 14 closed one chapter of Connecticut's cannabis tax experiment and opened another. The industry has reason for optimism. The real test comes on October 1, when consumers, operators, and the state's budget will all discover whether the numbers work as well in practice as they do on paper.