ISO compliance means following the ISO principals and guidelines  without the formalized certification and re-certification process.
While ISO certification provides independent validation of a company’s conformity to a set of standards  created by the International Organization for Standardization (ISO), the certification process can be long and extended. Thus, many organizations wants to get the ISO compliant document instead of ISO certification.
ISO compliance guidelines helps  on using the standards as a way to make decisions regarding policies, procedures, and processes so that they align with the specifications.A company can obtain a certificate of compliance that provides customers and business partners with assurance but lacks the time-consuming and costliness of the certification audit. For example, organizations can meet the requirements of the ISO 9000 management standard and obtain the certificate of compliance. This certificate can be used to prove that the appropriate organizational structures exist to promote improvement.

 Internal Compliance

 ISO guidelines  are adopted  in many industries. Furthermore, ISO certification creates reputation  that the business adheres to certain quality measures when developing and producing products and delivering services. Still, the decision to comply lies solely with the organization. Internal compliance indicates that the company's workforce and stakeholders are   trained and encouraged   to follow the rules and regulations set out by ISO. While non-compliance may not be legally penalized, actions may be taken internally for any breach in compliance. Internal compliance is not a proof of compliance with the ISO and is not legally recognized.

 Certification
To be recognized as an ISO-compliant business, the company must undergo an audit by an accreditation firm which is ISO certified.  The audit helps the business to do gap analysis and correct them if certification is denied because of the shortcomings. Companies can use the ISO certification as a public relations tool  and branding as well . It ensures suppliers and customers that the procedures used by the business are at par  with international standards.

 Ongoing Compliance

Once the certificate of compliance is achieved by a business house , the work does not stop. To maintain its status, the business will need to submit to regular audits at regular sets of intervals. The company must also continuously monitor its activities and document all operations so that it can maintain proper records. ISO auditors will review these records for accuracy and to ensure that the company is eligible to maintain its ISO-compliant status.