<PAGE>
SEPARATE ACCOUNT KG
(KEMPER GATEWAY ADVISOR)
ALLMERICA FINANCIAL LIFE INSURANCE AND ANNUITY COMPANY
FIRST ALLMERICA FINANCIAL LIFE INSURANCE COMPANY
SUPPLEMENT TO PROSPECTUS DATED MAY 1, 2000
***
In the first paragraph under "J. ELECTING THE FORM OF ANNUITY AND THE ANNUITY
DATE" in DESCRIPTION OF THE CONTRACT the following is added:
In New York, the latest possible annuitization age will not exceed the
Owner's age 90 and, in the case of Joint Owners, the age of the oldest
Owner will determine the Annuity Date.
* * *
The second paragraph under "L. ANNUITY BENEFIT PAYMENTS" under DESCRIPTION OF
THE CONTRACT is deleted in its entirety and replaced with the following:
For all options except a death benefit annuity, the dollar amount of the
first periodic annuity benefit payment is the Accumulated Value applied
under that option, after application of any Market Value Adjustment and
less premium tax, if any, and, for all commutable period certain options
and any noncommutable fixed period certain option of less than ten
years, further reduced by the Contract Fee. For a death benefit annuity,
the Annuity Value is the amount of the death benefit. Notwithstanding
the above, under a New York Contract, the dollar amount of the first
periodic annuity benefit payment will be equal to the greater of (a) or
(b) where (a) is equal to the Surrender Value and (b) is equal to 95% of
the Accumulated Value. In addition, under a New York Contract, annuity
benefit payments will not be less than payments that would be provided
at that time by the application of an Annuity Value equal to an amount
required to purchase any single payment immediate annuity contract
offered by the Company to all Owners of the same class.
* * *
The definition of the "j" factor in the calculation of the Market Value
Adjustment under GUARANTEE PERIOD ACCOUNTS is revised as follows:
For New York Contracts, "j" is the New Guaranteed Interest Rate,
expressed as a decimal, for a Guarantee Period with a duration equal to
the number of years remaining in the current Guarantee Period, rounded
to the nearest number of whole years.
* * *
Supplement dated December 14, 2000