Withdrawals under a ratio withdrawal plan are based on the current portfolio value, ensuring the fund is never fully depleted unless a 100% payout ratio is used. The feedback from the document states:

"Under a ratio withdrawal plan, the ratio is always based on the current portfolio value. Technically, this means that clients will never fully exhaust their mutual fund investment under this type of plan. Only in the unrealistic situation of a 100% payout ratio would the fund be completely paid out."