You can redeem part or all of the value of your zero-percent certificate of indebtedness at any time, with one exception: if you purchased all or a portion of your zero-percent certificate of indebtedness through a debit using the ACH method, you may not schedule a redemption from your zero-percent certificate of indebtedness within five business days after the date of the debit entry.
31 C.F.R. §363.144