The obligation to audit accounts for companies is established in the aforementioned commercial regulations and in the legislation on auditing accounts, i.e. Law 22/2015 of July 20 on auditing accounts and its implementing regulations.

Firstly, and in accordance with the provisions of article 263 of Legislative Royal Decree 1/2010, of July 2, approving the revised text of the Law on Capital Companies, “the annual accounts and the management report must be audited by the auditors”, the exception to this obligation being “companies which meet at least two of the following requirements on the closing date of two consecutive financial year:

1. The total of the asset items does not exceed two million eight hundred and fifty thousand euros.
2. The net amount of the annual turnover does not exceed five million seven hundred thousand euros.
3. The average number of workers employed during the year does not exceed fifty.

Companies will lose this faculty if they fail to meet two of the circumstances referred to in the previous paragraph for two consecutive financial years.
Companies may prepare abridged balance sheets and statements of changes in net assets in the first financial year after their incorporation, transformation or merger, if, at the close of said financial year, they meet at least two of the three circumstances expressed in the previous section.

In companies that do not need to be audited because they do not meet the limits defined in the preceding paragraphs, shareholders that represent at least five per cent of the share capital may apply to the company registrar responsible for the registered office of the company to appoint an auditor, at the expense of the company, to audit the annual accounts for a given financial year, provided that three months have not elapsed since the closing date of that financial year.

In addition to the provisions of the preceding paragraphs, the auditing of accounts is mandatory for entities in the cases mentioned below, regardless of their legal nature:

1. Those that issue securities which can be traded on official secondary securities markets or multilateral trading systems.
2. Those that issue publicly offered bonds.
3. Those that habitually engage in financial intermediation and, in any event, credit institutions, investment service companies, companies governing official secondary markets, entities governing multilateral trading systems, the Central Securities Depository for the Register of Securities and Clearing & Settlement of Trades, central counterparties, the Sociedad de Bolsas, investment guarantee funds management companies and other financial institutions, including collective investment institutions, securitisation funds and their managers, registered in the corresponding Registers of the Bank of Spain and the Spanish National Securities Commission.
4. Those whose corporate purpose is any activity subject to the revised text of the Law on the Management and Supervision of Private Insurance, approved by Royal Legislative Decree 6/2004 of October 29, within the limits established by regulation, as well as pension funds and their managing entities.

5. Those that, being obliged to prepare annual accounts in accordance with the regulatory framework of financial reporting that applies to them, have received subsidies or public aid during a financial year for a cumulative amount in excess of 600,000 euros. They must audit the annual accounts for that financial year.
6. Those that, being obliged to prepare annual accounts in accordance with the regulatory framework of financial reporting that applies to them, have entered into agreements with the public sector during a social year for a cumulative amount in excess of 600,000 euros and this represents more than 50% of their turnover. They must audit the annual accounts for that financial year and the following ones.