It depends.

From an MLS perspective, owner/agent must be noted in REALTOR® remarks and cannot be noted in public remarks. The prohibition in public remarks is due to IDX agreements. If a consumer is finding your listing on another broker's website and sees "owner agent" in public remarks, the consumer is likely to leave the source website and go to the listing agent thinking they will get a "better deal."

From License Law - Rule 3.3 D. When a licensee is advertising their own property for sale, purchase or exchange which is not listed with a broker, the licensee must indicate that he or she is licensed. The disclosure of licensee’s status must be made in all forms of advertising enumerated in Rule 3.3 (A), including the “for sale” sign.

In addition to disclosing their licensed status in all advertisements, licensees are required to disclose their licensed status on all real estate contracts in which they have an ownership interest.

From the REALTOR® Code of Ethics - Article12-6. REALTORS®, when advertising unlisted real property for sale/lease in which they have an ownership interest, shall disclose their status as both owners/landlords and as REALTORS® or real estate licensees.