(a) The present value of any paid-up annuity benefit available under an annuity contract on the date annuity payments are to begin may not be less than the minimum nonforfeiture amount for that contract on that date as computed under Subchapter B.
(b) The present value of the paid-up annuity benefit shall be computed using the mortality table, if any, and the interest rates specified in the contract for computing the minimum paid-up annuity benefit guaranteed by the contract.