To develop an internal audit plan that aligns with ISO 9001 standards, focusing on the most critical areas for compliance, you can follow these steps:

1. **Conduct a GAP Analysis**: Determine the extent to which your organization already complies with ISO 9001:2015. This will help identify areas that need attention.

2. **Establish a Project Plan**: Define activities, deadlines, and other relevant information needed to address the gaps identified in the GAP analysis.

3. **Plan the Audit Schedule**: Develop a schedule that outlines when each part of the Quality Management System (QMS) will be audited.

4. **Plan the Process Audit**: Identify the processes that are most critical to your organization and have the highest probability of nonconformities. Pay special attention to complex processes.

5. **Define Audit Criteria and Scope**: Clearly define what will be audited and against which criteria (e.g., specific clauses of ISO 9001:2015).

6. **Ensure Auditor Competence**: Make sure your internal auditors are competent and do not audit their own work. They should be knowledgeable about ISO 9001:2015 and good auditing practices.

7. **Conduct the Audit**: Follow the planned schedule and process, ensuring that all requirements of the standard are covered.

8. **Report on the Audit**: Document the findings and communicate them to relevant management.

9. **Follow-up on Issues or Improvements Found**: Address any nonconformities or areas for improvement identified during the audit.

10. **Conduct Management Review**: After the audit, review the findings with management to ensure that corrective actions are taken and the QMS is effectively maintained.

By following these steps, you can ensure that your internal audit plan is aligned with ISO 9001 standards and focuses on the most critical areas for compliance.