It depends on the size of your company and the complexity of the data you maintain.
A small-to-medium-sized business can expect to be audit-ready in an average of four months, then through the audit process in six months. Larger organizations might require a year or more.
Those four months of audit preparation typically involve scoping your ISMS, conducting risk assessments and gap analyses, designing and implementing controls, training staff, and preparing documentation.
The six-month certification audit is broken down into two stages. During Stage 1 audits, the auditor reviews ISMS documentation to make sure policies and procedures are designed properly. They may also make suggestions for how the organization can improve its ISMS to make it more secure.
During a Stage 2 audit, the auditor reviews business processes and controls to ensure compliance with ISO 27001’s ISMS and Annex A requirements.