1. The retirement board shall fix and determine by proper rules and regulations how much service in any year is equivalent to one year of service. In no case shall more than one year of service be creditable for all service rendered in one calendar year. The retirement board shall not allow credit as service for any period during which the member was absent without compensation, except as provided in subsection 3 of this section and subsection 3 of section 86.1500.

2. Except as provided in subsection 3 of section 86.1500, creditable service at retirement on which the retirement allowance of a member is based consists of the membership service rendered by such member since such member last became a member.

3. Except as provided in subsection 3 of section 86.1500, if a member is on leave of absence without compensation, such member shall not receive service credits for such time unless such member shall return to active service and purchase such creditable service at the actuarial cost. The actuarial cost shall be determined at the time the member makes such purchase.

4. Creditable service also includes any prior service credit to which a member may be entitled by virtue of an authorized purchase of such credit or as otherwise provided in sections 86.1310 to 86.1640.

5. Creditable service shall not include any time a member was suspended from service without compensation. No contribution is required from either the member under section 86.1400 or from the city under section 86.1390 for such time.