Regulatory Matters (Tables)

6 Months Ended

Mar. 31, 2025

Regulated Operations [Abstract]

Schedule of Regulatory Assets and Liabilities

The following regulatory assets and regulatory liabilities were reflected in the balance sheets of the Company, Spire Missouri and Spire Alabama as of March 31, 2025, September 30, 2024, and March 31, 2024.

	March 31,		September 30,		March 31,
Spire	2025		2024		2024
Regulatory Assets:
Current:
Unamortized purchased gas adjustments	$	0.3	$	28.9	$	81.4
Other		42.0		86.5		35.5
Total Current Regulatory Assets		42.3		115.4		116.9
Noncurrent:
Pension and postretirement benefit costs		241.3		237.5		251.4
Cost of removal		679.9		668.2		649.2
Future income taxes due from customers		153.7		150.7		146.6
Energy efficiency		63.6		61.0		58.2
Unamortized purchased gas adjustments		—		1.2		—
Other		148.7		133.2		167.3
Total Noncurrent Regulatory Assets		1,287.2		1,251.8		1,272.7
Total Regulatory Assets	$	1,329.5	$	1,367.2	$	1,389.6
Regulatory Liabilities:
Current:
Unamortized purchased gas adjustments	$	46.3	$	42.3	$	19.8
Other		5.3		7.2		5.3
Total Current Regulatory Liabilities		51.6		49.5		25.1
Noncurrent:
Deferred taxes due to customers		107.1		114.2		120.9
Pension and postretirement benefit costs		256.1		232.9		192.6
Accrued cost of removal		138.5		133.6		133.5
Unamortized purchased gas adjustments		100.2		17.2		90.8
Other		35.1		37.6		19.9
Total Noncurrent Regulatory Liabilities		637.0		535.5		557.7
Total Regulatory Liabilities	$	688.6	$	585.0	$	582.8

	March 31,		September 30,		March 31,
Spire Missouri	2025		2024		2024
Regulatory Assets:
Current:
Unamortized purchased gas adjustments	$	—	$	28.1	$	81.0
Other		15.5		55.9		8.2
Total Current Regulatory Assets		15.5		84.0		89.2
Noncurrent:
Future income taxes due from customers		145.9		142.7		138.5
Pension and postretirement benefit costs		175.0		166.5		183.6
Energy efficiency		63.6		61.0		58.2
Unamortized purchased gas adjustments		—		1.2		—
Cost of removal		93.5		97.0		97.0
Other		135.8		119.6		153.2
Total Noncurrent Regulatory Assets		613.8		588.0		630.5
Total Regulatory Assets	$	629.3	$	672.0	$	719.7
Regulatory Liabilities:
Current:
Unamortized purchased gas adjustments	$	12.0	$	10.2	$	—
Total Current Regulatory Liabilities		12.0		10.2		—
Noncurrent:
Deferred taxes due to customers		95.3		101.8		108.3
Pension and postretirement benefit costs		221.6		196.6		165.4
Accrued cost of removal		97.8		94.5		95.8
Unamortized purchased gas adjustments		100.2		17.2		90.8
Other		31.2		33.2		15.0
Total Noncurrent Regulatory Liabilities		546.1		443.3		475.3
Total Regulatory Liabilities	$	558.1	$	453.5	$	475.3

	March 31,		September 30,		March 31,
Spire Alabama	2025		2024		2024
Regulatory Assets:
Current:
Other	$	13.8	$	19.2	$	14.9
Total Current Regulatory Assets		13.8		19.2		14.9
Noncurrent:
Future income taxes due from customers		1.7		1.8		1.9
Pension and postretirement benefit costs		63.9		68.2		64.2
Cost of removal		586.4		571.2		552.2
Other		0.5		0.8		0.8
Total Noncurrent Regulatory Assets		652.5		642.0		619.1
Total Regulatory Assets	$	666.3	$	661.2	$	634.0
Regulatory Liabilities:
Current:
Unamortized purchased gas adjustments	$	33.4	$	30.9	$	18.7
Other		0.5		2.9		—
Total Current Regulatory Liabilities		33.9		33.8		18.7
Noncurrent:
Pension and postretirement benefit costs		23.6		25.1		16.8
Other		2.8		3.2		3.3
Total Noncurrent Regulatory Liabilities		26.4		28.3		20.1
Total Regulatory Liabilities	$	60.3	$	62.1	$	38.8

Schedule of Regulatory Assets Not Earning Return

A portion of the Company’s and Spire Missouri’s regulatory assets are not earning a return, as shown in the table below:

	March 31,		September 30,		March 31,
	2025		2024		2024
Spire
Pension and postretirement benefit costs	$	129.9	$	129.7	$	133.8
Future income taxes due from customers		152.0		148.9		144.7
Unamortized purchased gas adjustments		—		29.3		81.0
Other		113.8		132.5		127.7
Total Regulatory Assets Not Earning a Return	$	395.7	$	440.4	$	487.2
Spire Missouri
Pension and postretirement benefit costs	$	129.9	$	129.7	$	133.8
Future income taxes due from customers		145.9		142.7		138.5
Unamortized purchased gas adjustments		—		29.3		81.0
Other		113.8		132.5		127.7
Total Regulatory Assets Not Earning a Return	$	389.6	$	434.2	$	481.0