Promotion and Expansion of Private Employee Ownership Act of 2023 This bill accelerates to the enactment date of this bill the deferral of tax (currently, after December 31, 2027) on sales of employer stock to employee stock ownership plans (ESOPs) sponsored by S corporations. It also eliminates the limitation on the amount that may be deferred. The Department of the Treasury must establish the S Corporation Employee Ownership Assistance Office to foster increased employee ownership of S corporations. The office must provide education and outreach about the benefits of employee ownership of S corporations and technical assistance to assist S corporations in sponsoring ESOPs. The bill directs the Department of Labor to appoint an Advocate for Employee Ownership.