The short answer is “no” they are not required. At this time, we cannot find any regulation requiring them.
California Health and Safety Code Section 114250 and California Building Code Section 1115B.8.4 address the issue of toilet accessories, but we don’t find any regulation requiring paper/tissue toilet seat covers. Be careful the accessories that you do provide as they can lead to arson fires and clogged plumbing.
114250. Clean toilet rooms in good repair shall be provided and conveniently located and accessible for use by employees during all hours of operation. The number of toilet facilities required shall be in accordance with applicable local building and plumbing ordinances. Toilet rooms shall not be used for the storage of food, equipment, or supplies. Toilet tissue shall be provided in a permanently installed dispenser at each toilet.