Exhibit (12)(a)
CMS ENERGY CORPORATION
Ratio of Earnings to Combined Fixed Charges and Preferred Dividends
(Millions of Dollars)
<Table>
<Caption>
Year Ended December 31
------------------------------------
2006 2005 2004 2003 2002
----- ----- ----- ----- -----
(b) (c) (d) (e)
Earnings as defined (a)
Pretax income from continuing operations $(343) $(706) $ 137 $ 16 $(433)
Exclude equity basis subsidiaries (14) (17) (88) (41) (39)
Fixed charges as defined, adjusted to
exclude capitalized interest of $10,
$38, $(25), $9, and $16 million for the
years ended December 31, 2006, 2005,
2004, 2003, and 2002,
respectively (f) 529 505 649 605 518
----- ----- ----- ----- -----
Earnings as defined $ 172 $(218) $ 698 $ 580 $ 46
===== ===== ===== ===== =====
Fixed charges as defined (a)
Interest on long-term debt $ 483 $ 506 $ 560 $ 531 $ 404
Estimated interest portion of lease rental 7 6 4 7 10
Other interest charges 38 21 49 61 34
Preferred dividends 11 10 11 15 86
----- ----- ----- ----- -----
Fixed charges as defined $ 539 $ 543 $ 624 $ 614 $ 534
===== ===== ===== ===== =====
Ratio of earnings to combined fixed
charges and preferred dividends -- -- 1.12 -- --
===== ===== ===== ===== =====
</Table>
NOTES:
(a) Earnings and fixed charges as defined in instructions for Item 503 of
Regulation S-K.
(b) For the year ended December 31, 2006, fixed charges exceeded earnings by
$367 million. Earnings as defined include $459 million of asset impairment
charges, $404 million in mark-to-market losses related to our interest in
the MCV Partnership, and a $200 million charge related to our agreement to
settle shareholder class action lawsuits.
(c) For the year ended December 31, 2005, fixed charges exceeded earnings by
$761 million. Earnings as defined include $1.184 billion of asset
impairment charges.
(d) For the year ended December 31, 2003, fixed charges exceeded earnings by
$34 million. Earnings as defined include $95 million of asset impairment
charges.
(e) For the year ended December 31, 2002, fixed charges exceeded earnings by
$488 million. Earnings as defined include $602 million of asset impairment
charges.
(f) For 2004, fixed charges, adjusted as defined, include $25 million of
interest cost that was capitalized prior to 2004 and subsequently expensed
in 2004.