The GMIB base is the notional value used to compute income under a Guaranteed Minimum Income Benefit. It is distinct from account value and typically grows by a contractual roll-up rate or by periodic step-ups to the highest anniversary value. The base is subject to rider rules-withdrawals,allocation constraints, and fees can reduce or suspend growth. When the owner annuities under the rider, the insurer uses the base (and the rider's payout factors) to set guaranteed income. The base cannot be withdrawn in cash and exists only to determine minimum income amounts under the rider.

Annual statements show the GMIB base and any roll-up or step-ups. Advisors confirm allocation rules are followed and avoid withdrawals that would reduce the base before income begins. They coordinate the annuitization date with other retirement income sources.