Providers who are reimbursed on the basis of cost reports shall submit to the Department or its designee, in the form prescribed, financial and statistical data within 3 months after the end of the provider's fiscal year unless the Department grants the provider an extension or the provider discontinues participation in the Program. If a provider discontinues participation, financial and statistical data shall be submitted to the Department within 45 days after the effective date of termination. An extension shall be granted upon written request by the provider, setting forth the specific reasons for the request, if the Department determines, taking into consideration the totality of the circumstances, that the request is reasonable. Availability of Records. The provider shall keep all records available for inspection or audit by the Department or the Department's designee at any reasonable time during normal business hours. Documentation of Costs. Upon request by the Department or the Department's designee, the provider shall make documentation of costs available during the course of verification. The provider shall have 30 days from the date of the request to provide this documentation. Costs for which documentation is not provided within the 30 days shall be considered not allowable. Upon written demonstration by the provider of good cause, the Department may grant, in writing, an extension of time to provide the requested documentation. Records shall be retained for 6 years after the month in which the cost report to which the materials apply is filed with the Department or the Department's designee.