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Retirement Benefit Obligations
 9 Months Ended
Sep. 30, 2025
Retirement Benefits [Abstract]  
Retirement Benefit Obligations

Note 9: Retirement Benefit obligations

The Company co-sponsors the Unitil Corporation Retirement Plan (Pension Plan), the Unitil Retiree Health and Welfare Benefits Plan (PBOP Plan), and the Unitil Corporation SERP to provide certain pension and postretirement benefits for its retirees and current employees. Please see Note 9 to the Consolidated Financial Statements in the Company’s Form 10-K for the year ended December 31, 2024 as filed with the SEC on February 10, 2025 for additional information regarding these plans.

The following table includes the key weighted average assumptions used in determining the Company’s benefit plan costs and obligations:

 

Used to Determine Plan Costs

 

2025

 

 

2024

 

Discount Rate

 

 

5.60

%

 

 

5.00

%

Rate of Compensation Increase

 

 

3.00

%

 

 

3.00

%

Expected Long-term rate of return on plan assets

 

 

7.50

%

 

 

7.50

%

 

The health care cost trend rate used to determine benefit plan costs for 2025 for pre-65 retirees is 8.50%, with an ultimate rate of 4.50% in 2034, and for post-65 retirees, the health care cost trend rate is 7.50%, with an ultimate rate of 4.50% in 2034. The health care cost trend rate used to determine benefit plan costs for 2024 for pre-65 retirees was 8.00%, with an ultimate rate of 4.50% in 2033, and for post-65 retirees, the health care cost trend rate was 6.00%, with an ultimate rate of 4.50% in 2033.

The following tables provide the components of the Company’s Retirement plan costs ($000’s):

 

 

Pension Plan

 

 

PBOP Plan

 

 

SERP

 

For the Three Months Ended September 30,

 

2025

 

 

2024

 

 

2025

 

 

2024

 

 

2025

 

 

2024

 

Service Cost

 

$

436

 

 

$

498

 

 

$

502

 

 

$

497

 

 

$

39

 

 

$

53

 

Interest Cost

 

 

2,016

 

 

 

1,887

 

 

 

992

 

 

 

817

 

 

 

172

 

 

 

180

 

Expected Return on Plan Assets

 

 

(2,624

)

 

 

(2,649

)

 

 

(1,086

)

 

 

(970

)

 

 

—

 

 

 

—

 

Prior Service Cost Amortization

 

 

63

 

 

 

80

 

 

 

—

 

 

 

—

 

 

 

3

 

 

 

4

 

Actuarial Loss Amortization

 

 

320

 

 

 

361

 

 

 

(187

)

 

 

(218

)

 

 

(54

)

 

 

—

 

Sub-total

 

 

211

 

 

 

177

 

 

 

221

 

 

 

126

 

 

 

160

 

 

 

237

 

Amounts Capitalized and Deferred

 

 

6

 

 

 

30

 

 

 

(64

)

 

 

(8

)

 

 

(51

)

 

 

(73

)

Net Periodic Benefit Cost Recognized

 

$

217

 

 

$

207

 

 

$

157

 

 

$

118

 

 

$

109

 

 

$

164

 

 

 

 

Pension Plan

 

 

PBOP Plan

 

 

SERP

 

For the Nine Months Ended September 30,

 

2025

 

 

2024

 

 

2025

 

 

2024

 

 

2025

 

 

2024

 

Service Cost

 

$

1,308

 

 

$

1,492

 

 

$

1,505

 

 

$

1,491

 

 

$

118

 

 

$

162

 

Interest Cost

 

 

6,048

 

 

 

5,659

 

 

 

2,976

 

 

 

2,451

 

 

 

516

 

 

 

542

 

Expected Return on Plan Assets

 

 

(7,873

)

 

 

(7,947

)

 

 

(3,257

)

 

 

(2,908

)

 

 

—

 

 

 

—

 

Prior Service Cost Amortization

 

 

191

 

 

 

242

 

 

 

—

 

 

 

—

 

 

 

7

 

 

 

8

 

Actuarial Loss Amortization

 

 

958

 

 

 

1,085

 

 

 

(561

)

 

 

(655

)

 

 

(161

)

 

 

—

 

Sub-total

 

 

632

 

 

 

531

 

 

 

663

 

 

 

379

 

 

 

480

 

 

 

712

 

Amounts Capitalized and Deferred

 

 

141

 

 

 

165

 

 

 

(98

)

 

 

170

 

 

 

(152

)

 

 

(221

)

Net Periodic Benefit Cost Recognized

 

$

773

 

 

$

696

 

 

$

565

 

 

$

549

 

 

$

328

 

 

$

491

 

 

Employer Contributions

As of September 30, 2025, the Company had made contributions of $3.9 million and $0.6 million to its Pension Plan and PBOP Plan, respectively, in 2025. The Company, along with its subsidiaries, expects to make contributions to its Pension and PBOP Plans in 2025 and future years at minimum required and discretionary funding levels consistent with the amounts recovered in the distribution utilities’ rates for these Pension and PBOP Plan costs.

As of September 30, 2025, the Company had made $0.5 million of benefit payments under the SERP Plan in 2025. The Company presently anticipates making an additional $0.2 million of benefit payments under the SERP Plan in 2025.