Cost of gas adjustment factor rates

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

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 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 off-peak period, please download the Historical GAF Data Excel Workbook.
  • For GAF and LDAF rates currently in effect for the 2017 off-peak period, please see below.

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

Proposed GAF and LDAF rates have been filed but not yet approved by the Department.  The proposed rates can be viewed in the DPU's Fileroom.  The rates will be posted here once they are approved.

Off-Peak 2017 Rev. 3 (Effective 10/1/17)

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

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.1175 0.2108
R-3, R-4 $/Therm 0.1990 0.2108
G-40 $/Therm 0.1990 0.1103
G-41 $/Therm 0.1990 0.0744
G-42 $/Therm 0.1990 0.0654
G-43 $/Therm 0.1990 0.0581
G-50 $/Therm 0.1175 0.1103
G-51 $/Therm 0.1175 0.0744
G-52 $/Therm 0.1175 0.0654
G-53 $/Therm 0.1175 0.0581

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.1300 0.2170
R-3, R-4 $/Therm 0.1190 0.2170
G-41 $/Therm 0.1190 0.1130
G-42 $/Therm 0.1190 0.0870
G-43 $/Therm 0.1190 0.0660
G-51 $/Therm 0.1300 0.1130
G-52 $/Therm 0.1300 0.0870
G-53 $/Therm 0.1300 0.0660
T-54 $/Therm   0.0130

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.4991 0.1993
R-3, R-4 $/Ccf 0.4991 0.1806
G-1, S-1 $/Ccf 0.4991 0.0855

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4203 0.4174
R-3, R-4 $/Therm 0.4240 0.4174
G-41 $/Therm 0.4240 0.2925
G-42 $/Therm 0.4240 0.1517
G-43 $/Therm 0.4240 0.1375
G-51 $/Therm 0.4203 0.2925
G-52 $/Therm 0.4203 0.1517
G-53 $/Therm 0.4203 0.1375

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.1965 0.2694
G-41, G-42, G-43 $/Therm 0.1965 0.1772
G-51, G-52, G-53 $/Therm 0.1965 0.1244

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.2994 0.3494
G-41B/E, G-51B/E $/Therm 0.2994 0.1964
G-42B/E, G-52B/E $/Therm 0.2994 0.1677
G-43B/E, G-53B/E $/Therm 0.2994 0.1530
G-44B, G-54B $/Therm 0.1909 0.1268
G-44B, G-54B $/MDCQ 1.2751  


National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.2862 0.3185
G-41, G-51 $/Therm 0.2862 0.1422
G-42, G-52 $/Therm 0.2862 0.1071
G-43, G-53 $/Therm 0.2862 0.0730


NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3148 0.2539
G-41, G-51 $/Therm 0.3148 0.1035
G-42, G-52 $/Therm 0.3148 0.0724
G-43, G-53, T-1 $/Therm 0.3148 0.0636

Off-Peak 2017 Rev. 2 (Effective 8/1/17)

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

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.2044 0.2108
R-3, R-4 $/Therm 0.2859 0.2108
G-40 $/Therm 0.2859 0.1103
G-41 $/Therm 0.2859 0.0744
G-42 $/Therm 0.2859 0.0654
G-43 $/Therm 0.2859 0.0581
G-50 $/Therm 0.2044 0.1103
G-51 $/Therm 0.2044 0.0744
G-52 $/Therm 0.2044 0.0654
G-53 $/Therm 0.2044 0.0581

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.1300 0.2170
R-3, R-4 $/Therm 0.1190 0.2170
G-41 $/Therm 0.1190 0.1130
G-42 $/Therm 0.1190 0.0870
G-43 $/Therm 0.1190 0.0660
G-51 $/Therm 0.1300 0.1130
G-52 $/Therm 0.1300 0.0870
G-53 $/Therm 0.1300 0.0660
T-54 $/Therm   0.0130

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.4991 0.1993
R-3, R-4 $/Ccf 0.4991 0.1806
G-1, S-1 $/Ccf 0.4991 0.0855

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4203 0.4174
R-3, R-4 $/Therm 0.4240 0.4174
G-41 $/Therm 0.4240 0.2925
G-42 $/Therm 0.4240 0.1517
G-43 $/Therm 0.4240 0.1375
G-51 $/Therm 0.4203 0.2925
G-52 $/Therm 0.4203 0.1517
G-53 $/Therm 0.4203 0.1375

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.1965 0.2694
G-41, G-42, G-43 $/Therm 0.1965 0.1772
G-51, G-52, G-53 $/Therm 0.1965 0.1244

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3675 0.3494
G-41B/E, G-51B/E $/Therm 0.3675 0.1964
G-42B/E, G-52B/E $/Therm 0.3675 0.1677
G-43B/E, G-53B/E $/Therm 0.3675 0.1530
G-44B, G-54B $/Therm 0.2845 0.1268
G-44B, G-54B $/MDCQ 0.8083  

National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3543 0.3185
G-41, G-51 $/Therm 0.3543 0.1422
G-42, G-52 $/Therm 0.3543 0.1071
G-43, G-53 $/Therm 0.3543 0.0730

NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3148 0.2539
G-41, G-51 $/Therm 0.3148 0.1035
G-42, G-52 $/Therm 0.3148 0.0724
G-43, G-53, T-1 $/Therm 0.3148 0.0636

Off-Peak 2017 Rev. 1 (Effective 6/1/17)

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

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.2044 0.2108
R-3, R-4 $/Therm 0.2859 0.2108
G-40 $/Therm 0.2859 0.1103
G-41 $/Therm 0.2859 0.0744
G-42 $/Therm 0.2859 0.0654
G-43 $/Therm 0.2859 0.0581
G-50 $/Therm 0.2044 0.1103
G-51 $/Therm 0.2044 0.0744
G-52 $/Therm 0.2044 0.0654
G-53 $/Therm 0.2044 0.0581

Berkshire Gas Company

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.2050 0.2170
R-3, R-4 $/Therm 0.1870 0.2170
G-41 $/Therm 0.1870 0.1130
G-42 $/Therm 0.1870 0.0870
G-43 $/Therm 0.1870 0.0660
G-51 $/Therm 0.2050 0.1130
G-52 $/Therm 0.2050 0.0870
G-53 $/Therm 0.2050 0.0660
T-54 $/Therm   0.0130

Blackstone Gas Company

Rate Class Billing Unit GAF LDAF
R-1. R-2 $/Ccf 0.4991 0.1993
R-3, R-4 $/Ccf 0.4991 0.1806
G-1, S-1 $/Ccf 0.4991 0.0855

Fitchburg Gas d/b/a Unitil

Rate Class Billing Unit GAF LDAF
R-1, R-2 $/Therm 0.4203 0.4174
R-3, R-4 $/Therm 0.4240 0.4174
G-41 $/Therm 0.4240 0.2925
G-42 $/Therm 0.4240 0.1517
G-43 $/Therm 0.4240 0.1375
G-51 $/Therm 0.4203 0.2925
G-52 $/Therm 0.4203 0.1517
G-53 $/Therm 0.4203 0.1375

Liberty Utilities

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.1965 0.2694
G-41, G-42, G-43 $/Therm 0.1965 0.1772
G-51, G-52, G-53 $/Therm 0.1965 0.1244

National Grid - Boston Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.4210 0.3494
G-41B/E, G-51B/E $/Therm 0.4210 0.1964
G-42B/E, G-52B/E $/Therm 0.4210 0.1677
G-43B/E, G-53B/E $/Therm 0.4210 0.1530
G-44B, G-54B $/Therm 0.3455 0.1268
G-44B, G-54B $/MDCQ 0.7297  

National Grid - Colonial Gas

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.4078 0.3185
G-41, G-51 $/Therm 0.4078 0.1422
G-42, G-52 $/Therm 0.4078 0.1071
G-43, G-53 $/Therm 0.4078 0.0730

NSTAR Gas Company d/b/a Eversource Energy

Rate Class Billing Unit GAF LDAF
Residential $/Therm 0.3148 0.2539
G-41, G-51 $/Therm 0.3148 0.1035
G-42, G-52 $/Therm 0.3148 0.0724
G-43, G-53, T-1 $/Therm 0.3148 0.0636

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