Annual Financial Audit by professional

Is there any law in Virginia that requires a outside audit of the financials records for a non stock corporation association? Our association has usually conducted one but it has continually been later and later in the fiscal year. I asked about the 2015 audit and the response by management was that an audit for 2015 had not been conducted. To me it is part of a sound business practice just wondering if it is required in any way. The only place in our documents an audit is mentioned is under duties of the treasurer and it states in part that the treasurer shall keep proper books of account, cause an audit of the association books to be made by a public accountant if so required by a mortgagee.

Thanks Tim. Your knowledge is always appreciated.