<PAGE>   1
                                                                    Exhibit (12)
                             CMS ENERGY CORPORATION
                Ratio of Earnings to Fixed Charges and Preferred
                     Securities Dividends and Distributions
                              (Millions of Dollars)


<TABLE>
<CAPTION>
                                               Nine Months
                                                    Ended        /---------- Years Ended December 31 ----------/
                                        September 30, 1999       1998       1997      1996       1995       1994
                                        ------------------------------------------------------------------------
<S>                                                 <C>        <C>        <C>       <C>        <C>        <C>
                                                                   (b)
Earnings as defined (a)
Consolidated net income                              $ 256      $ 242      $ 244     $ 224      $ 195      $ 177
Income taxes                                            91        100        108       137        113         91
Exclude equity basis subsidiaries                      (53)       (92)       (80)      (85)       (57)       (18)
Fixed charges as defined, adjusted to
  exclude capitalized interest of $34, $28, $13,
  $5, $4 and $2 million for the nine months
  ended September 30, 1999 and for the years ended
  December 31, 1998, 1997, 1996, 1995
  and 1994, respectively                               413        395        360       313        299        253
                                                     -----------------------------------------------------------

Earnings as defined                                  $ 707      $ 645      $ 632     $ 589      $ 550      $ 503
                                                     ===========================================================


Fixed charges as defined (a)
Interest on long-term debt                           $ 365      $ 319      $ 273     $ 230      $ 224      $ 193
Estimated interest portion of lease rental               4          8          8        10          9          9
Other interest charges                                  38         48         49        43         42         30
Preferred securities dividends and
  distributions                                         62         77         67        54         42         36
                                                     -----------------------------------------------------------

Fixed charges as defined                             $ 469      $ 452      $ 397     $ 337      $ 317      $ 268
                                                     ===========================================================


Ratio of earnings to fixed charges and
 preferred securities dividends and distributions     1.51       1.43       1.59      1.75       1.74       1.88
                                                     ===========================================================

</TABLE>

NOTES:
(a) Earnings and fixed charges as defined in instructions for Item 503 of
Regulation S-K.

(b) Excludes a cumulative effect of change in accounting after-tax gain of $43
million.