In the US, carbon credits are bought in two very different settings. Anyone can buy voluntary credits to compensate for their own emissions. Separately, a handful of states run compliance markets for power plants and big emitters. This guide covers both, the main US registries, and the federal and California rules on offset claims. For other countries, see our countries hub.
US compliance markets
US emissions trading runs at state and regional level: ICAP’s 2025 status report lists state systems, such as California and Washington, rather than a federal oneSource 14.
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| Scheme | Covers | Offset limit |
|---|---|---|
| California Cap-and-Invest | Economy-wide large emitters; linked with Québec | 6% of obligation (2026–2030) |
| RGGI | Power plants of 25 MW or more in 11 states | Up to 3.3% of obligation |
| Washington Cap-and-Invest | Businesses emitting 25,000 tCO₂ or more a year | Up to 8% (2023–2026) |
As of Oct 2026
California Cap-and-Invest
California’s Cap-and-Invest Program was formerly called Cap-and-TradeSource 11. Compliance obligations started in January 2013, and the programme has been linked with Québec’s since January 2014Source 4. In September 2025 the state adopted AB 1207, which extends the programme’s provisions until 1 January 2046Source 5.
Covered companies can use offset credits for up to 8% of their obligation for emissions through 2020, 4% for 2021–2025 and 6% for 2026–2030Source 6.
Regional Greenhouse Gas Initiative (RGGI)
RGGI is a cooperative effort among Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont and Virginia to cap and reduce power-sector CO₂Source 12. Virginia’s participation has been the subject of litigationSource 14. Offsets can help companies meet up to 3.3% of their compliance obligationsSource 12.
Washington Cap-and-Invest
Washington’s programme started on 1 January 2023, with the first allowance auction on 28 February that yearSource 13. In the first compliance period, 2023–2026, emitters can generally cover up to 8% of their emissions with offsetsSource 7. Washington, California and Québec have signed a linkage agreement and expect to begin operating a shared market in 2027Source 8.
Allowances are not offsets
Allowances in these markets are permits that covered companies need. To compensate for your own emissions, you buy voluntary credits. Our guide to voluntary vs compliance markets explains the difference.
Buying voluntary credits in the US
Individuals and businesses can buy from online retailers, marketplaces and brokers. Several of the main voluntary registries are US-based:
- ACR describes itself as the world’s first carbon registry, working in carbon markets since 1996, and is an approved Offset Project Registry in California and WashingtonSource 15.
- Climate Action Reserve began as the California Climate Action Registry, created by the State of California in 2001Source 16.
- Verra runs the Verra Registry for credits under its standardsSource 17.
Compliance allowances and offsets in the linked California and Québec programmes are tracked in CITSS, the Western Climate Initiative’s tracking systemSource 18.
Whichever provider you use, ask which registry holds your credits and check the record yourself. Our guide to how to verify carbon credits shows how, and where to buy compares providers.
Reduce first, then offset
Cut what you can before you buy, and use credits for what’s left. Our guide for individuals shows how to size a purchase.
Claims and tax notes
What you can say about offsets
The FTC’s Green Guides include a section on carbon offsets. Sellers should use competent and reliable scientific and accounting methods to quantify reductions and must not sell the same reduction more than once. They should clearly disclose when an offset represents reductions that won’t occur for two years or longer, and it is deceptive to claim a reduction that was required by lawSource 20.
The Guides were last revised in 2012, when carbon offset guidance was added, and the FTC has sought comment on possible updatesSource 9. In California, AB 1305 requires businesses that market or sell voluntary offsets in the state, or make net zero or similar claims, to disclose specified information on their websitesSource 21.
On tax, we found no specific IRS guidance on buying carbon offsets. Under the IRS’s general rules, you can deduct contributions only if you make them to a qualified organization, and only the amount above the value of any benefit you receiveSource 19. Ask a tax adviser before claiming a deduction.
How to check quality before you buy
Each Verra credit represents one tonne of CO₂e reduced or removedSource 1, and registries such as Gold Standard’s track every credit from issuance to retirementSource 2. That makes three checks possible before you pay:
- Is it in a public registry? Ask for the registry and serial numbers, and check the credits are retired in your name.
- Is the method credible? The ICVCM’s Core Carbon Principles set a quality threshold, and credits that meet it can carry the CCP labelSource 3.
- Is the seller clear? A good seller says what you are buying, what it charges and how and in whose name it retires credits.
Our quality section explains each check, and carbon credit scams lists the warning signs.
Article 6 deals
We found no US bilateral agreement under Article 6 of the Paris Agreement. The US notified its withdrawal from the Paris Agreement on 27 January 2025, and the withdrawal took effect on 27 January 2026Source 10.
For countries that have signed Article 6 agreements, see Switzerland, Singapore and Japan.
How to buy, step by step
Step 1: Work out what to cover
Estimate your footprint and cut what you can first.
Step 2: Choose a project type
Pick credits from a standard and project type you trust.
Step 3: Pick a provider
Compare retailers, marketplaces and brokers on registry serials and certificates.
Step 4: Check the registry record
Confirm the credits are retired in your name on ACR, the Reserve, Verra or another registry.