NOX allowances may be banked for future use or transfer in a compliance account, an overdraft account, or a general account, as follows:
(a) Any NOX allowance that is held in a compliance account, an overdraft account, or a general account will remain in such account unless and until the NOX allowance is deducted or transferred under Sec. 97.31, Sec. 97.54, Sec. 97.56, or subpart G or I of this part.
(b) The Administrator will designate, as a ``banked'' NOX allowance, any NOX allowance that remains in a compliance account, an overdraft account, or a general account after the Administrator has made all deductions for a given control period from the compliance account or overdraft account pursuant to Sec. 97.54 (except deductions pursuant to Sec. 97.54(d)(2)) and that was allocated for that control period or a control period in a prior year.