Can ISO 27001:2013 be certified against multiple legal entities?

It is possible to have a single certification for multiple companies, provided that the ISMS scope covers elements of all companies (e.g., processes, information, and/or locations). Of course, all entities will have to go through all certification process together.

Adopting a single certificate for all entities or separate ones for each entity is a business decision, depending on their objectives and strategies, but in general, organizations adopt the model of one certification for each entity, because a change in an entity does not impact the certification of other entities.

These articles will provide you a further explanation about scope definition:

• How to define the ISMS scope https://advisera.com/27001academy/knowledgebase/how-to-define-the-isms-scope/
• Problems with defining the scope in ISO 27001 https://advisera.com/27001academy/blog/2010/06/29/problems-with-defining-the-scope-in-iso-27001/

This article will provide an additional explanation about single certification for multiples entities (although it is about ISO 9001, the same concept applies to ISO 27001):

• Certifying different legal entities under one certification scope in ISO 9001 https://advisera.com/9001academy/blog/2018/03/27/certifying-different-legal-entities-under-one-certification-scope-in-iso-9001/ 

These articles will provide you a further explanation about implementing ISO 27001:

• What is ISO 27001 https://advisera.com/27001academy/what-is-iso-27001/
• ISO 27001 implementation checklist https://advisera.com/27001academy/knowledgebase/iso-27001-implementation-checklist/
• How long does it take to implement ISO 27001 / BS 25999? https://advisera.com/27001academy/blog/2011/11/08/how-long-does-it-take-to-implement-iso-27001-bs-25999/ - this is the timing that is needed for companies that use our toolkits

These materials will also help you regarding ISO 27001 implementation:

• Book Secure & Simple: A Small-Business Guide to Implementing ISO 27001 On Your Own https://advisera.com/books/secure-and-simple-a-small-business-guide-to-implementing-iso-27001-on-your-own/
• ISO 27001 Free online training ISO 27001 Foundations Course http://training.advisera.com/course/iso-27001-foundations-course/

To see how documents used to implement ISO 27001 looks like, please take a look at the free demo templates of our ISO 27001 Implementation Toolkit in this link: https://advisera.com/27001academy/iso-27001-documentation-toolkit/