A carbon tax and a cap-and-trade system are the two main ways governments put a price on greenhouse gas emissions, and the choice between them comes down to a single tradeoff: a carbon tax fixes the price per ton and accepts whatever emissions result, while cap and trade fixes the emissions total and accepts whatever price the market produces. Roughly 80 carbon pricing programs operate worldwide, split about evenly between the two designs.
How a Carbon Tax Works
The government picks a dollar amount per ton of greenhouse gas released, and every covered emitter pays that rate on its total output.1Carbon Pricing Dashboard. What is Carbon Pricing? A power plant that releases 50,000 tons of carbon dioxide in a year at a $50 tax rate owes $2.5 million. The math doesn’t depend on what other companies are doing.
Most proposals set a rate that rises on a preset schedule, climbing by a fixed amount each year. A business that knows the tax will be $50 this year, $60 next, and $70 the year after can run reliable projections on cleaner equipment. That predictability is the tax’s biggest selling point.
Collection can happen at different points in the supply chain. An upstream tax hits fuel producers and importers, covering a large share of emissions through a small number of taxpayers. A downstream tax reaches the facilities that actually burn the fuel. Upstream is far easier to administer, and the United States already levies excise taxes on petroleum at the refinery and import stage under 26 U.S.C. 4611, so a carbon tax could piggyback on existing machinery.2Office of the Law Revision Counsel. 26 U.S. Code 4611 – Imposition of Tax
The United States has no federal carbon tax. Canada, Sweden, and South Africa do, and rates around the world range from under $5 per ton to well over $100 per ton in parts of Scandinavia.
How Cap and Trade Works
Instead of naming a price, the government names a quantity. It sets a ceiling on total emissions, divides that ceiling into permits (usually one per metric ton of CO2), and distributes those permits to covered companies.3US EPA. How Do Emissions Trading Programs Work Each year the total number of permits shrinks, pushing overall emissions down on a set schedule regardless of what happens to prices.
Permits enter circulation two ways. Most are auctioned, with companies bidding against each other. Some are given away free to industries considered at risk of moving operations abroad. After distribution, companies trade permits on a secondary market. A factory that cuts emissions cheaply can sell its leftover permits to a refinery facing higher costs. That trading is what creates the carbon price, and it moves with supply and demand.
At the end of each compliance period, every covered facility must surrender enough permits to cover its verified emissions. A company that falls short must buy more on the open market or face penalties well above the market price. That surrender-or-pay structure is what makes the cap enforceable.3US EPA. How Do Emissions Trading Programs Work
The EU Emissions Trading System is the largest program by value, with allowance prices recently averaging around €77 per ton.4European Commission. Auctioning of Allowances China launched the largest system by emissions volume in 2021. Regional cap-and-trade programs run in the U.S. Northeast and on the West Coast, with per-ton prices from the low $20s to over $30.
The Core Tradeoff Between Price Certainty and Emissions Certainty
This is where the choice actually matters. A carbon tax guarantees what pollution will cost but cannot guarantee how much emissions will fall. Cap and trade guarantees that emissions stay under the cap but cannot guarantee what permits will cost.1Carbon Pricing Dashboard. What is Carbon Pricing? No design delivers both certainties.
For businesses planning multi-decade investments in low-carbon equipment, price certainty is worth a lot. A stable carbon price makes financial projections reliable. Under cap and trade, the same company might hold back because a permit price swing could turn a smart investment into a bad one. Research on the EU market has found that price volatility can delay clean-energy projects for a decade or more.
For governments trying to hit a specific tonnage target by a specific deadline, emission certainty is more valuable. Cap and trade can be calibrated to hit an exact number because the cap itself is the mechanism. A carbon tax has to guess at the right rate, and if the guess is off, emissions either overshoot the target or the tax turns out higher than needed. Some tax proposals address this with a ratcheting mechanism that raises the rate automatically if emissions don’t fall fast enough.
Hybrid Designs That Blur the Line
In practice, many cap-and-trade programs bolt on features borrowed from the tax side. A price floor sets a minimum auction price so permits don’t collapse in value during a downturn; the largest U.S. program set its 2026 auction floor at $34.12. A price ceiling, sometimes called a cost containment reserve, caps how high permit prices can climb before the government releases extra permits. Once a program has both a floor and a ceiling, it starts to resemble a carbon tax that fluctuates within a band.
Offsets
Most cap-and-trade programs let companies use carbon offsets to meet part of their obligation. An offset credit represents a verified ton of reductions outside the capped sector, such as a forestry project or landfill methane capture. Offsets lower compliance costs by tapping cheaper opportunities, but if a project doesn’t deliver, the cap effectively loosens. Programs manage that risk by limiting the share of an obligation that can be met with offsets and by requiring independent verification.
Administrative Cost and Complexity
A carbon tax is cheaper and simpler to run. It rides on tax collection systems that already assess and enforce excise taxes on fuel. A few hundred upstream fuel producers file returns, and the government processes payments through channels that have worked for decades.
Cap and trade needs all of that emissions monitoring plus separate infrastructure for creating, tracking, and transferring permits. The government has to run auctions, maintain a registry of ownership, oversee secondary-market trading, verify surrendered allowances against reported emissions, and police fraud. Applied upstream to a small number of fuel suppliers, the burden stays manageable. Applied downstream to individual plants and factories, the number of regulated entities grows sharply. An upstream program might cover 500 to 750 companies; a downstream approach could touch millions of sources.
The added complexity is what enables trading in the first place, and trading is what makes cap and trade efficient. Companies that can cut emissions cheaply do so and sell permits to companies that can’t, so reductions happen wherever they cost least. A carbon tax achieves the same efficiency only if the rate is set correctly, and setting the rate requires information the government may not have.
What Happens to the Revenue
Both systems generate significant government revenue, carbon taxes through direct payments and cap-and-trade programs through permit auctions. How the money gets used shapes the program’s political viability as much as its environmental design does.
Revenue often flows into a general fund and gets allocated through the normal budget process. That gives legislators flexibility but offers no assurance the money supports the energy transition.
Cap-and-trade auction proceeds are more commonly earmarked for environmental spending: public transit, renewable energy research, and community sustainability projects. The Greenhouse Gas Reduction Fund created under the Inflation Reduction Act directed $27 billion toward clean energy financing, and state cap-and-trade programs have channeled billions from auctions into similar investment accounts.5US EPA. Greenhouse Gas Reduction Fund
A third model, sometimes called a carbon dividend, returns the revenue directly to households as equal monthly payments. Every dollar collected from emitters goes back to the public, offsetting higher energy costs. Supporters argue the approach is revenue-neutral and politically durable because most households, especially lower-income ones, receive more in dividends than they pay in higher prices. Canada and Switzerland operate versions of this model.
Carbon Leakage and Border Adjustments
A domestic carbon price alone doesn’t stop emissions from moving abroad. If a steel mill pays $50 per ton but competes against imports from a country with no carbon price, the playing field tilts toward the unpriced imports. Production and emissions migrate to weaker regulatory jurisdictions, a dynamic called carbon leakage.
Border carbon adjustments answer this by charging importers for the emissions embedded in their goods. The European Union’s Carbon Border Adjustment Mechanism entered its definitive phase on January 1, 2026, covering cement, iron and steel, aluminum, fertilizers, electricity, and hydrogen. Importers report the embedded emissions and surrender certificates priced at the quarterly average of EU ETS auction prices.6European Commission. Carbon Border Adjustment Mechanism If the exporting country already charges a carbon price, that amount can be deducted from the certificates owed. The United States has no comparable federal mechanism, though the EU system reaches any American manufacturer exporting into it in the covered sectors.
Where the U.S. Stands
There is no federal carbon tax and no federal cap-and-trade program in the United States. The regional programs on the West Coast and in the Northeast are the operational examples, running at per-ton prices in the $20s and low $30s.
Whichever design a jurisdiction adopts, it depends on accurate emissions data. Under 40 CFR Part 98, facilities that emit 25,000 metric tons or more of CO2 equivalent per year must file annual reports with the EPA.7eCFR. 40 CFR 98.2 – Who Must Report? That threshold captures large power plants, refineries, and heavy industrial operations while excluding most small businesses; the agricultural sector and land-use activities are also excluded.8Environmental Protection Agency. Greenhouse Gases Reporting Program Implementation Rule Overview The program covers Scope 1 emissions, meaning greenhouse gases from sources a facility owns or controls. Scope 2 emissions from purchased electricity are tracked for corporate inventory purposes but reported differently.9US EPA. Scope 1 and Scope 2 Inventory Guidance
Facilities submit through the EPA’s electronic Greenhouse Gas Reporting Tool. The agency doesn’t require independent third-party verification; each reporter self-certifies and the EPA runs statistical checks to flag potential errors.10Environmental Protection Agency. Greenhouse Gas Reporting Program Implementation That reporting infrastructure is what either pricing system would build on if Congress ever adopted one at the federal level.