Exhibit 12a

UNS Energy Corporation

Computation of Ratio of Earnings to Fixed Charges

	12 Months Ended
	December 31, 2012		December 31, 2011		December 31, 2010		December 31, 2009		December 31, 2008		December 31, 2007
	- Thousands of Dollars -
Fixed Charges:
Interest on Long-Term Debt	$	71,909	$	73,217	$	65,020	$	58,134	$	70,227	$	73,095
Other Interest (1)		1,954		2,535		1,651		3,468		1,837		5,480
Interest on Capital Lease Obligations		36,593		44,874		52,540		53,682		57,272		64,499
Estimated Interest Portion of Rental Expense		691		926		240		345		188		258
Total Fixed Charges	$	111,147	$	121,552	$	119,451	$	115,629	$	129,524	$	143,332
Net Income	$	90,919	$	109,975	$	112,984	$	105,901	$	16,955	$	60,712
Add (Deduct):
Losses from Equity Investees		7		—		5,570		1,834		713		340
Income Tax Expense		55,727		66,951		76,921		63,232		18,747		40,274
Total Fixed Charges		111,147		121,552		119,451		115,629		129,524		143,332
Total Earnings before Taxes and Fixed Charges	$	257,800	$	298,478	$	314,926	$	286,596	$	165,939	$	244,658
Ratio of Earnings to Fixed Charges		2.319		2.456		2.636		2.479		1.281		1.707

⁽¹⁾  Excludes recognition of Allowance for Borrowed Funds Used During Construction and Loss on Extinguishment of Debt.