Under immediate supervision (Office Assistant I), general supervision (Office Assistant II), or direction (Office Assistant III), performs a variety of clerical and administrative duties in support of an assigned functional area; serves at the front counter and on the phone, answers inquiries, and responds to complaints from the public; reviews and routes mail and phone calls to appropriate staff; processes invoices, purchase orders, billings, time sheets, and office supply orders; collects fees and payments from the public; provides information and assistance to the general public; and performs related work as required. Positions in the Office Assistant class series are flexibly staffed; positions at the Office Assistant II level are normally filled by advancement from the Office Assistant I level; progression to the Office Assistant II level is dependent on (i) management affirmation that the position is performing the full range of duties assigned to the classification; (ii) satisfactory work performance; (iii) the incumbent meeting the minimum qualifications for the classification including any licenses and certifications; and (iv) management approval for progression to the Office Assistant II level.