Exhibit 12a

UniSource Energy Corporation
Computation of Ratio of Earnings to Fixed Charges

	9 Months Ended			12 Months Ended				12 Months Ended(2)
	Sep. 30,			Sep. 30,		Dec. 31,		Dec. 31,			Dec. 31,			Dec. 31,			Dec. 31,
	2008			2008		2007		2006			2005			2004			2003
	- Thousands of Dollars -
Fixed Charges:
Interest on Long-Term Debt	$	53,603		$	71,965	$	73,095	$	75,039		$	76,762		$	80,968		$	80,844
Other Interest (1)		1,375			2,088		5,480		7,922			3,153			1,947			3,709
Interest on Capital Lease Obligations		42,969			59,079		64,499		72,586			79,098			85,912			84,080
Total Fixed Charges	$	97,947		$	133,132	$	143,074	$	155,547		$	159,013		$	168,827		$	168,633
Net Income (Loss)	$	(8,906	)	$	7,301	$	58,373	$	67,447		$	46,144		$	45,919		$	113,941
Less:
Discontinued Operations — Net of Tax		—			—		—		(1,796	)		(5,483	)		(5,063	)		(7,472	)
Accounting Change — Net of Tax		—			—		—		—			(626	)		—			67,471
Net Income/(Loss) from Continuing Operations		(8,906	)		7,301		58,373		69,243			52,253			50,982			53,942
Add (Deduct):
(Income) Losses from Equity Investees (2)		315			458		340		(210	)		(2,113	)		(7,121	)		3,051
Income Taxes		(1,106	)		10,296		39,079		43,936			37,623			37,186			16,531
Total Fixed Charges		97,947			133,132		143,074		155,547			159,013			168,827			168,633
Total Earnings before Taxes and Fixed Charges	$	88,250		$	151,187	$	240,866	$	268,516		$	246,776		$	249,874		$	242,157
Ratio of Earnings to Fixed Charges		0.901			1.136		1.684		1.726			1.552			1.480			1.436

(1)	Excludes recognition of Allowance for Borrowed Funds Used During Construction.
(2)	The information previously reported has been reclassified for the discontinued operations of Global Solar, Inc.