EXHIBIT 12(a) BANKBOSTON CORPORATION COMPUTATION OF CONSOLIDATED RATIO OF EARNINGS TO FIXED CHARGES (Excluding Interest on Deposits) The Corporation's ratios of earnings to fixed charges (excluding interest on deposits) for the nine months ended September 30, 1998 and 1997 and for the five years ended December 31, 1997 were as follows: Nine Months Ended September 30, Years Ended December 31, ----------------- ------------------------------------------------ (Dollars in millions) 1998 1997 1997 1996 1995 1994 1993 ------- ------- ------- ------- ------- ------- -------- Net income $ 585 $ 645 $ 879 $ 650 $ 678 $ 542 $ 367 Extraordinary items, net of tax 7 Cumulative effect of changes in accounting principles, net of tax (24) Income tax expense 360 434 589 483 529 422 262 ------- ------- ------- ------- ------- ------- -------- Pretax earnings $ 945 $ 1,079 $ 1,468 $ 1,133 $ 1,207 $ 971 $ 605 ======= ======= ======= ======= ======= ======= ======== Fixed charges: Portion of rental expense (net of sublease rental income) which approximates the interest factor $ 31 $ 29 $ 39 $ 40 $ 38 $ 35 $ 36 Interest on borrowed funds 884 783 1,050 873 1,079 1,038 384 ------- ------- ------- ------- ------- ------- -------- Total fixed charges $ 915 $ 812 $ 1,089 $ 913 $ 1,117 $ 1,073 $ 420 ======= ======= ======= ======= ======= ======= ======== Earnings (for ratio calculation) $ 1,860 $ 1,891 $ 2,557 $ 2,046 $ 2,324 $ 2,044 $ 1,025 ======= ======= ======= ======= ======= ======= ======== Total fixed charges $ 915 $ 812 $ 1,089 $ 913 $ 1,117 $ 1,073 $ 420 ======= ======= ======= ======= ======= ======= ======== Ratio of earnings to fixed charges 2.03 2.33 2.35 2.24 2.08 1.90 2.44 ======= ======= ======= ======= ======= ======= ======== For purposes of computing the consolidated ratio of earnings to fixed charges "earnings" represent income before extraordinary items and cumulative effect of changes in accounting principles plus applicable income taxes and fixed charges. "Fixed charges" include gross interest expense (excluding interest on deposits) and the proportion deemed representative of the interest factor of rent expense, net of income from subleases.