Peer Review applies to all types of assurances services. Assurance services means as defined in “Framework to Assurance Engagements”  — Which included 2 types Reasonable Assurance (Audit) & Limited Assurance (Review & Others).
Other assignments are left out as they are not part of assurance services and public interest is not involved.
 
Filing return is not assurance service, management consultancy & compilation are also not assurance services.