Partial withdrawals reduce the guarantee base. The reduction is calculated proportionately, not dollar-for-dollar. This is a commonly tested nuance.
Proportionate reduction example: A contract has a $100,000 guarantee base and a current market value of $80,000. The owner withdraws $16,000 (20% of the market value). The guarantee base is reduced by 20%: from $100,000 to $80,000.
Exam trap: The guarantee base reduction is proportionate to the market value withdrawn, not a flat dollar deduction from the guarantee base. A withdrawal of $10,000 from a fund worth $100,000 reduces a $120,000 guarantee base by 10%, to $108,000 -- not to $110,000.