American Century Government Income Trust

STATEMENT OF ADDITIONAL INFORMATION SUPPLEMENT

CAPITAL PRESERVATION FUND * GOVERNMENT AGENCY MONEY MARKET FUND
GOVERNMENT BOND FUND * TREASURY FUND * INFLATION-ADJUSTED BOND FUND
SHORT-TERM GOVERNMENT FUND * GINNIE MAE FUND

Supplement dated April 7, 2003 * Statement of Additional Information dated July 31, 2002

The following is added before the sub-heading Adjustable-Rate Mortgage Loans
(ARMS) on page 10 of the Statement of Additional Information.

COMMERCIAL MORTGAGE-BACKED SECURITIES (CMBS)

CMBS are securities created from a pool of commercial mortgage loans, such as
loans for hotels, shopping centers, office buildings, apartment buildings, and
the like. Interest and principal payments from these loans are passed on to the
investor according to a particular schedule of payments. The credit quality of
CMBS depends primarily on the quality of the underlying loans and on the
structure of the particular deal. Generally, deals are structured with senior
and subordinate classes. Rating agencies that rate the individual classes of the
deal determine the amount of subordination of a particular class. Commercial
mortgages are generally structured with prepayment penalties, which greatly
reduces prepayment risk to the investor. However, the value of these securities
may change because of actual or perceived changes in the creditworthiness of the
individual borrowers, their tenants, the servicing agents, or the general state
of commercial real estate.

The following is added before the heading Inflation-Indexed Treasury Securities
on page 11 of the Statement of Additional Information.

Asset-Backed Securities (ABS)

ABS are structured like mortgage-backed securities, but instead of mortgage
loans or interests in mortgage loans, the underlying assets may include, for
example, such items as motor vehicle installment sales or installment loan
contracts, leases of various types of real and personal property, home equity
loans, student loans, small business loans, and receivables from credit card
agreements. The ability of an issuer of asset-backed securities to enforce its
security interest in the underlying assets may be limited. The value of an ABS
is affected by changes in the market's perception of the assets backing the
security, the creditworthiness of the servicing agent for the loan pool, the
originator of the loans, or the financial institution providing any credit
enhancement.

Payments of principal and interest passed through to holders of ABS are
typically supported by some form of credit enhancement, such as a letter of
credit, surety bond, limited guarantee by another entity or a priority to
certain of the borrower's other securities. The degree of credit enhancement
varies, and generally applies to only a fraction of the asset-backed security's
par value until exhausted. If the credit enhancement of an ABS held by a fund
has been exhausted, and if any required payments of principal and interest are
not made with respect to the underlying loans, the fund may experience losses or
delays in receiving payment.

Some types of ABS may be less effective than other types of securities as a
means of "locking in" attractive long-term interest rates. One reason is the
need to reinvest prepayments of principal; another is the possibility of
significant unscheduled prepayments resulting from declines in interest rates.
These prepayments would have to be reinvested at lower rates. As a result, these
securities may have less potential for capital appreciation during periods of
declining interest rates than other securities of comparable maturities,
although they may have a similar risk of decline in market value during periods
of rising interest rates. Prepayments may also significantly shorten the
effective maturities of these securities, especially during periods of declining
interest rates. Conversely, during periods of rising interest rates, a reduction
in prepayments may increase the effective maturities of these securities,
subjecting them to a greater risk of decline in market value in response to
rising interest rates than traditional debt securities, and, therefore,
potentially increasing the volatility of the fund.

The risks of investing in ABS are ultimately dependent upon the repayment of the
underlying loans by the individual or corporate borrowers. Although the fund
would generally have no recourse against the entity that originated the loans in
the event of default by a borrower, ABS typically are structured to mitigate
this risk of default.

The following is added before the heading Investment Policies on page 15 of the
Statement of Additional Information.

Derivative Securities

To the extent permitted by its investment objectives and policies, each fund may
invest in securities that are commonly referred to as derivative securities.
Generally, a derivative security is a financial arrangement, the value of which
is based on, or derived from, a traditional security, asset, or market index.

Certain derivative securities are described more accurately as structured
investments. A structured investment is a security whose value or performance is
linked to an underlying index or other security or asset class. Structured
investments include asset-backed securities (ABS), asset-backed commercial paper
(ABCP), commercial and residential mortgage-backed securities (MBS),
collateralized mortgage obligations (CMO), collateralized debt obligations (CDO),
collateralized loan obligations (CLO), and securities backed by other types of
collateral. Structured investments involve the transfer of specified financial
assets to a special purpose entity, generally a corporation or trust, or the
deposit of financial assets with a custodian; and the issuance of securities or
depository receipts backed by, or representing interests in those assets.

Some structured investments are individually negotiated agreements or are traded
over-the-counter. Structured investments may be organized and operated to
restructure the investment characteristics of the underlying security. The cash
flow on the underlying instruments may be apportioned among the newly issued
structured securities to create securities with different investment
characteristics, such as varying maturities, payment priorities and interest
rate provisions, and the extent of such payments made with respect to structured
securities is dependent on the extent of the cash flow on the underlying
instruments. Investments in structured securities generally involve a class of
structured securities that is either subordinated or unsubordinated to the right
of payment of another class. Subordinated structured securities typically have
higher yields and present greater risks than unsubordinated structured
securities. Structured securities are also subject to such risks as the
inability or unwillingness of the issuers of the underlying securities to repay
principal and interest, and requests by the issuers of the underlying securities
to reschedule or restructure outstanding debt and to extend additional loan
amounts.

The fund may buy structured investments based on unleveraged structures,
provided the security has investment characteristics consistent with the
particular fund's investment policies, and represents an interest in a pool of
financial assets that are permitted investments of that fund.

Some derivative securities are in many respects like any other debt security,
although they may be more volatile or less liquid than more traditional debt
securities.

There are many different types of derivative securities and many different ways
to use them. Futures and options are commonly used for traditional hedging
purposes to attempt to protect a fund from exposure to changing interest rates,
securities prices or currency exchange rates, and for cash management purposes
as a low-cost method of gaining exposure to a particular securities market
without investing directly in those securities.

The fund may not invest in a derivative security unless the reference index or
the instrument to which it relates is an eligible investment for the fund. For
example, a security whose underlying value is liked to the price of oil would
not be a permissible investment because the funds may not invest in oil and gas
leases or futures. The return on a derivative security may increase or decrease,
depending upon changes in the reference index or instrument to which it relates.

There are a range of risks associated with investments in derivative securities,
including:

* the risk that the underlying security, interest rate, market index or other
  financial asset will not move in the direction the fund managers anticipate;

* the possibility that there may be no liquid secondary market, or the
  possibility that price fluctuation limits may be imposed by the exchange,
  either of which may make it difficult or impossible to close out a position
  when desired;

* the risk that adverse price movements in an instrument can result in a loss
  substantially greater than a fund's initial investment; and

* the risk that the counterparty will fail to perform its obligations.

The Board of Trustees has approved the advisor's policy regarding investments in
derivative securities. That policy specifies factors that must be considered in
connection with a purchase of derivative securities and provides that a fund may
not invest in a derivative security if it would be possible for a fund to lose
more money than it had invested. The policy also establishes a committee that
must review certain proposed purchases before the purchases can be made. The
advisor will report on fund activity in derivative securities to the Board of
Trustees as necessary.

Restricted and Illiquid Securities

Each fund may, from time to time, purchase restricted or illiquid securities,
including Rule 144A securities, when they present attractive investment
opportunities that otherwise meet the fund's criteria for selection. Rule 144A
securities are securities that are privately placed with and traded among
qualified institutional investors rather than the general public. Although Rule
144A securities are considered "restricted securities," they are not necessarily
illiquid.

With respect to securities eligible for resale under Rule 144A, the staff of the
Securities and Exchange Commission (SEC) has taken the position that the
liquidity of such securities in the portfolio of a fund offering redeemable
securities is a question of fact for the Board of Trustees to determine, such
determination to be based upon a consideration of the readily available trading
markets and the review of any contractual restrictions. Accordingly, the Board
of Trustees is responsible for developing and establishing the guidelines and
procedures for determining the liquidity of Rule 144A securities. As allowed by
Rule 144A, the Board of Trustees has delegated the day-to-day function of
determining the liquidity of Rule 144A securities to the fund managers. The
board retains the responsibility to monitor the implementation of the guidelines
and procedures it has adopted.

Because the secondary market for restricted securities is generally limited to
certain qualified institutional investors, the liquidity of such securities may
be limited accordingly and a fund may, from time to time, hold a Rule 144A or
other security that is illiquid. In such an event, the fund managers will
consider appropriate remedies to minimize the effect on such fund's liquidity.

The following is added after the Non-Money Market Fund Yields chart on page 38.

The funds also may elect to advertise an annualized distribution rate, computed
by multiplying the ordinary dividends earned by a fund over a 30-day period
(excluding capital gains) by 12, dividing that number by the fund's share price
(net asset value or maximum offering price) at the end of the period, and then
multiplying that amount by 100:

(Dividends Earned Over Last 30 Days  X  12)
-------------------------------------------  X  100  =  Annualized Distribution Rate
          Current Share Price

The annualized distribution rate for a fund will differ from the fund's 30-day
SEC yield. The annualized distribution rate for C Class shares of a fund assumes
no CDSC is paid.

SH-SPL-334321  0304