Exhibit 12a

UniSource Energy Corporation
Computation of Ratio of Earnings to Fixed Charges

	12 Months Ended
	Dec. 31,		Dec. 31,		Dec. 31,		Dec. 31,			Dec. 31,			Dec. 31,
	2009		2008		2007		2006			2005			2004
	- Thousands of Dollars -
Fixed Charges:
Interest on Long-Term Debt	$	58,134	$	70,227	$	73,095	$	75,039		$	76,762		$	80,968
Other Interest (1)		3,468		1,837		5,480		7,922			3,153			1,947
Interest on Capital Lease Obligations		53,682		57,272		64,499		72,586			79,098			85,912
Estimated Interest Portion of Rental Expense		345		188		258		326			391			453
Total Fixed Charges	$	115,629	$	129,524	$	143,332	$	155,873		$	159,404		$	169,280
Net Income	$	104,258	$	14,021	$	58,373	$	67,447		$	46,144		$	45,919
Less:
Discontinued Operations — Net of Tax		—		—		—		(1,796	)		(5,483	)		(5,063	)
Accounting Change — Net of Tax		—		—		—		—			(626	)		—
Net Income from Continuing Operations		104,258		14,021		58,373		69,243			52,253			50,982
Add (Deduct):
(Income) Losses from Equity Investees		1,834		713		340		(210	)		(2,113	)		(7,121	)
Income Taxes		64,348		16,976		39,079		43,936			37,623			37,186
Total Fixed Charges		115,629		129,524		143,332		155,873			159,404			169,280
Total Earnings before Taxes and Fixed Charges	$	286,069	$	161,234	$	241,124	$	268,842		$	247,167		$	250,327
Ratio of Earnings to Fixed Charges		2.474		1.245		1.682		1.725			1.551			1.479

(1) Excludes recognition of Allowance for Borrowed Funds Used During Construction.