NY Part 253 Update: Enforcement Dates, the 100-Year GWP Shift, and Next Steps

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Nearly three months after the New York State Department of Environmental Conservation (NYSDEC) issued its enforcement discretion letter, the agency has not yet proposed the amended Part 253 rule, and the first emissions year ends on December 31. The extended enforcement dates give reporters more time to submit, not to collect data. For methane-heavy sources, the coming switch to a 100-year GWP could also change whether they must report or verify at all.

This alert updates KERAMIDA's earlier NY Part 253 overview and outlines which deadlines are affected, the two rule changes NYSDEC is preparing, what hasn’t changed, and what to do before year-end.

What NYSDEC Announced

On July 31, 2026, NYSDEC's Office of General Counsel issued an enforcement discretion letter for the Mandatory Greenhouse Gas Reporting Program, 6 NYCRR Part 253. The letter delays enforcement of six deadlines while NYSDEC amends the rule.

The trigger was the Legislature's May 26, 2026 amendment to the Climate Leadership and Community Protection Act (CLCPA) (L. 2026, ch. 58, pt. VV). NYSDEC's FAQ on the letter describes two changes that Part 253 must now reflect:

  • Carbon dioxide equivalents are measured over 100 years instead of 20.

  • Upstream out-of-state emissions from the extraction and transmission of fossil fuels are removed from statewide calculations.

An enforcement discretion letter cannot change the regulation itself. Amendments to Part 253 must go through the State Administrative Procedure Act, including public comment. Until the revised rule is final, the letter serves as a bridge.

Regulatory Deadlines vs. Enforcement Dates

Six deadlines have later enforcement dates; the regulatory dates in Part 253 remain unchanged. Dates are from NYSDEC's Mandatory Greenhouse Gas Reporting page.

NY Part 253 Deadlines and Enforcement Discretion

Requirement

Regulatory Deadline

Enforcement Discretion Through

Monitoring Plans and Registration

Initial Emissions Monitoring and Measurement Plans (EMMP) for waste facilities

September 1, 2026

March 1, 2027

Initial Large Emission Source GHG Monitoring Plans1

December 31, 2026

June 30, 2027

2026 Registration of specified sources for imported and exported electricity

February 1, 2027

August 31, 2027

Emissions Reports and Verification

2026 Emissions data report

June 1, 2027

December 31, 2027

2026 Verification statements1

December 1, 2027

April 1, 2028

2027 Emissions data report

June 1, 2028

September 1, 2028

2027 Verification statements1

December 1, 2028

No extension

1 Large Emission Sources include facilities emitting 25,000 metric tons CO2e or more per year and fuel suppliers above volume thresholds (15 million cubic feet of natural gas or of LNG and CNG combined, 100,000 gallons of liquid fuel, or 500 short tons of coal). These sources are also subject to annual third-party GHG verification.

The Shift to a 100-Year GWP and Who Is Covered

The move from a 20-year to a 100-year global warming potential could change who must report and who must verify. It aligns New York with the basis used by EPA and most international programs.

Part 253 currently takes its 20-year GWP values from the IPCC Fifth Assessment Report (AR5), through 6 NYCRR 496.5. For any gas not listed there, it uses values from the Sixth Assessment Report (AR6).

The effect is largest for methane. Under IPCC values, methane counts for more than 80 times CO₂ over 20 years and roughly 28 to 30 times over 100 years. A methane-heavy source will therefore show a much lower CO₂e total on the new basis.

That matters at two thresholds:

  • 10,000 metric tons CO₂e per year, where facility reporting begins.

  • 25,000 metric tons CO₂e per year, where a facility becomes a Large Emission Source and needs annual third-party verification.

There is a gap to manage carefully. The statute now specifies 100 years, but Part 253's text still uses the 20-year basis until NYSDEC finishes its rulemaking. NYSDEC has not yet published the amended factors or confirmed final thresholds. A borderline entity should keep collecting 2026 data and should not self-exempt from a rule that is mid-amendment.

Landfills, digesters, natural gas systems and other methane-driven operations near either line should re-screen applicability on a 100-year basis.

Fuel suppliers are not affected by this threshold change; their verification thresholds are based on fuel volumes rather than CO₂e.

The Upstream Emissions Change and Who Is Affected

The original CLCPA counted emissions that occur outside New York to produce and deliver the fossil fuels used in the state, such as methane released at wells, processing plants, and interstate pipelines. The amendment removes those upstream out-of-state emissions from the calculation of statewide greenhouse gas emissions.

Part 253 currently requires fuel suppliers, facilities, and electric power entities to report these upstream emissions by applying NYSDEC’s upstream emission factors to the fossil fuels they sell or use (§253-2.18). Once NYSDEC aligns the rule with the amended statute, that calculation is expected to be narrowed or removed, which would simplify reporting for all three groups. Fuel suppliers, whose reports cover the largest fuel volumes, are the most affected. Section 253-2.18 also covers fuel used to generate imported electricity, and it is not yet clear whether that portion will change.

Upstream emissions are mostly methane, so this change and the move to a 100-year GWP together could significantly lower the emissions attributed to natural gas used in New York. Until the amended rule is final, reporters should continue calculating upstream emissions as Part 253 currently requires.

What Has Not Changed

Part 253 remains in effect as written, and NYSDEC's FAQ says reporters must still report 2026 emissions data. The letter changes when NYSDEC will enforce certain deadlines, not what the rule requires.

  • 2026 is still the first emissions year. It is already underway, and the underlying activity data must be captured now.

  • Penalties still apply. Each unreported, late, incomplete, or inaccurate report remains a separate violation under the rule. Enforcement discretion covers only the specific deadlines listed above.

  • Verification still applies. Large Emission Sources still need annual third-party verification by a NYSDEC-accredited verifier.

  • The reporting platform is still coming. NYSDEC says NYS e-GGRT is in development and that it will provide training once the system is in place.

What to Do Now

The enforcement buffer is extra time to submit, not a reason to pause. We recommend five steps:

  1. Keep collecting 2026 data. Preserve fuel use, throughput, waste, and other activity records, and continue calculating upstream emissions as Part 253 currently requires.

  2. Re-screen applicability on both bases. Calculate CO₂e with 20-year and 100-year GWPs so you know where you stand on reporting and verification under both the current text and the expected amendment.

  3. Hold the original deadlines as your working targets. For deadlines that haven’t passed, treat the enforcement dates as contingency, especially for monitoring plans that shape data collection.

  4. Prepare for verification early. If you are near or above 25,000 metric tons CO₂e, a pre-verification review of your 2026 inventory reduces findings later.

  5. Watch the rulemaking. The proposal will set the final factors, thresholds, and dates, and it will be open for public comment.

How KERAMIDA Can Help

KERAMIDA supports Part 253 reporters with applicability and threshold assessments, GHG inventories, monitoring plan development, and pre-verification reviews. We also provide independent third-party verification of emissions data for Large Emission Sources.

If you are unsure how the enforcement dates or the 100-year GWP basis affect your facility, contact our team to talk it through.