Cost of Gas Adjustment Factor Rates and Information

Cost of Gas Adjustment (GAF) and Local Distribution Adjustment (LDAF) are semiannual rates charged by gas companies

Explanation of Rates

The Cost of Gas Adjustment Factor, or GAF, is the rate charged by gas companies to recover the cost to purchase and transport gas supply to Massachusetts.  

The peak period (or winter) rate is in effect from November 1st through April 30th, and the off-peak period (or summer) rate is in effect from May 1st through October 31st.  

A gas company may, at any time, submit an amended GAF filing to the Department of Public Utilities (DPU). The amended GAF filing must be submitted 7 business days before the first billing cycle of the month in which it is proposed to take effect.  220 CMR 6.12.

The Local Distribution Adjustment Factor, or LDAF, is the rate charged by gas companies to recover distribution-related costs such as energy efficiency, environmental response, Attorney General consultants, residential assistance, and the gas system enhancement replacement program.

For company-specific delivery/distribution rate information, including Revenue Decoupling, please see the DPU's Rates and Tariffs page.

Currently effective GAF and LDAF rates

  • For GAF and LDAF rates in effect prior to the 2017/18 peak period, please download the GAF Historical Data Workbook.
  • For GAF and LDAF rates currently in effect for the 2017/18 peak period, please see below.

Peak 2017-2018 Rev. 2 (Effective 2/1/18)

Bay State Gas d/b/a Columbia Gas of Massachusetts

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.8905 0.2254
R-3, R-4 $/Therm 0.9676 0.2254
G-40 $/Therm 0.9676 0.1323
G-41 $/Therm 0.9676 0.0886
G-42 $/Therm 0.9676 0.0779
G-43 $/Therm 0.9676 0.0656
G-50 $/Therm 0.8905 0.1323
G-51 $/Therm 0.8905 0.0886
G-52 $/Therm 0.8905 0.0779
G-53 $/Therm 0.8905 0.0656

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.5450 0.1780
R-3, R-4 $/Therm 0.6630 0.1780
G-41 $/Therm 0.6630 0.0920
G-42 $/Therm 0.6630 0.0690
G-43 $/Therm 0.6630 0.0520
G-51 $/Therm 0.5450 0.0920
G-52 $/Therm 0.5450 0.0690
G-53 $/Therm 0.5450 0.0520
T-54 $/Therm 0.5450 0.0120

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.7808 0.1417
R-3, R-4 $/Ccf 0.7808 0.1368
G-1, School Rate $/Ccf 0.7808 0.0668

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.6943 0.3076
R-3, R-4 $/Therm 0.7131 0.3076
G-41 $/Therm 0.7131 0.2051
G-42 $/Therm 0.7131 0.1141
G-43 $/Therm 0.7131 0.1050
G-51 $/Therm 0.6943 0.2051
G-52 $/Therm 0.6943 0.1141
G-53 $/Therm 0.6943 0.1050

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.8136 0.2963
G-41, G-42, G-43 $/Therm 0.8136 0.1971
G-51, G-52, G-53 $/Therm 0.8136 0.1389

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.8019 0.3418
G-41B/E, G-51B/E $/Therm 0.8019 0.2008
G-42B/E, G-52B/E $/Therm 0.8019 0.1730
G-43B/E, G-53B/E $/Therm 0.8019 0.1566
G-44B, G-54B $/Therm 0.5272 0.1349
G-44B, G-54B $/MDCQ 2.5581  

National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.8010 0.3017
G-41, G-51 $/Therm 0.8010 0.1443
G-42, G-52 $/Therm 0.8010 0.1105
G-43, G-53 $/Therm 0.8010 0.0741

NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.5718 0.2265
G-41, G-51 $/Therm 0.5718 0.1340
G-42, G-52 $/Therm 0.5718 0.1010
G-43, G-53, T-1 $/Therm 0.5718 0.0926

Peak 2017-2018 Rev. 1 (Effective 1/1/18)

Bay State Gas d/b/a Columbia Gas of Massachusetts

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4630 0.2254
R-3, R-4 $/Therm 0.5401 0.2254
G-40 $/Therm 0.5401 0.1323
G-41 $/Therm 0.5401 0.0886
G-42 $/Therm 0.5401 0.0779
G-43 $/Therm 0.5401 0.0656
G-50 $/Therm 0.4630 0.1323
G-51 $/Therm 0.4630 0.0886
G-52 $/Therm 0.4630 0.0779
G-53 $/Therm 0.4630 0.0656

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4750 0.1780
R-3, R-4 $/Therm 0.5780 0.1780
G-41 $/Therm 0.5780 0.0920
G-42 $/Therm 0.5780 0.0690
G-43 $/Therm 0.5780 0.0520
G-51 $/Therm 0.4750 0.0920
G-52 $/Therm 0.4750 0.0690
G-53 $/Therm 0.4750 0.0520
T-54 $/Therm 0.4750 0.0120

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.6690 0.1417
R-3, R-4 $/Ccf 0.6690 0.1368
G-1, School Rate $/Ccf 0.6690 0.0668

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.3948 0.3076
R-3, R-4 $/Therm 0.4136 0.3076
G-41 $/Therm 0.4136 0.2051
G-42 $/Therm 0.4136 0.1141
G-43 $/Therm 0.4136 0.1050
G-51 $/Therm 0.3948 0.2051
G-52 $/Therm 0.3948 0.1141
G-53 $/Therm 0.3948 0.1050

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3102 0.2963
G-41, G-42, G-43 $/Therm 0.3102 0.1971
G-51, G-52, G-53 $/Therm 0.3102 0.1389

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.6260 0.3418
G-41B/E, G-51B/E $/Therm 0.6260 0.2008
G-42B/E, G-52B/E $/Therm 0.6260 0.1730
G-43B/E, G-53B/E $/Therm 0.6260 0.1566
G-44B, G-54B $/Therm 0.3321 0.1349
G-44B, G-54B $/MDCQ 3.3781  

National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.6251 0.3017
G-41, G-51 $/Therm 0.6251 0.1443
G-42, G-52 $/Therm 0.6251 0.1105
G-43, G-53 $/Therm 0.6251 0.0741

NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.5718 0.2265
G-41, G-51 $/Therm 0.5718 0.1340
G-42, G-52 $/Therm 0.5718 0.1010
G-43, G-53, T-1 $/Therm 0.5718 0.0926

Peak 2017-2018 (Effective 11/1/17)

Bay State Gas d/b/a Columbia Gas of Massachusetts

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4630 0.2254
R-3, R-4 $/Therm 0.5401 0.2254
G-40 $/Therm 0.5401 0.1323
G-41 $/Therm 0.5401 0.0886
G-42 $/Therm 0.5401 0.0779
G-43 $/Therm 0.5401 0.0656
G-50 $/Therm 0.4630 0.1323
G-51 $/Therm 0.4630 0.0886
G-52 $/Therm 0.4630 0.0779
G-53 $/Therm 0.4630 0.0656

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4750 0.1780
R-3, R-4 $/Therm 0.5780 0.1780
G-41 $/Therm 0.5780 0.0920
G-42 $/Therm 0.5780 0.0690
G-43 $/Therm 0.5780 0.0520
G-51 $/Therm 0.4750 0.0920
G-52 $/Therm 0.4750 0.0690
G-53 $/Therm 0.4750 0.0520
T-54 $/Therm 0.4750 0.0120

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.6690 0.1417
R-3, R-4 $/Ccf 0.6690 0.1368
G-1, School Rate $/Ccf 0.6690 0.0668

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4288 0.3076
R-3, R-4 $/Therm 0.4476 0.3076
G-41 $/Therm 0.4476 0.2051
G-42 $/Therm 0.4476 0.1141
G-43 $/Therm 0.4476 0.1050
G-51 $/Therm 0.4288 0.2051
G-52 $/Therm 0.4288 0.1141
G-53 $/Therm 0.4288 0.1050

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3102 0.2963
G-41, G-42, G-43 $/Therm 0.3102 0.1971
G-51, G-52, G-53 $/Therm 0.3102 0.1389

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.6260 0.3418
G-41B/E, G-51B/E $/Therm 0.6260 0.2008
G-42B/E, G-52B/E $/Therm 0.6260 0.1730
G-43B/E, G-53B/E $/Therm 0.6260 0.1566
G-44B, G-54B $/Therm 0.3321 0.1349
G-44B, G-54B $/MDCQ 3.3781  

National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.6251 0.3017
G-41, G-51 $/Therm 0.6251 0.1443
G-42, G-52 $/Therm 0.6251 0.1105
G-43, G-53 $/Therm 0.6251 0.0741

NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.5718 0.2279
G-41, G-51 $/Therm 0.5718 0.1342
G-42, G-52 $/Therm 0.5718 0.1012
G-43, G-53, T-1 $/Therm 0.5718 0.0926

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