Designed to ensure annual accounts give a "true and fair view" of the state of affairs within an organisation, an audit is an official inspection of financial accounts by an independent and accredited outsider.

The auditor's responsibilities include the provision of "reasonable assurance" that the financial information provided is free from material misstatements, whether due to fraud or error. Accountants are usually quick to point out that while reasonable assurance is a high threshold, it is not a guarantee that an audit will always detect omissions or irregularities.

All publicly-listed companies and the majority of private limited companies in the UK are required to have an external audit of their annual accounts. In general, private organisations are required to do so if they meet two of the following three criteria: an annual turnover in excess of £10.2 million; total assets in excess of £5.1m; or if they employ more than 50 people.

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According to the last set of accounts published by the SNP in August 2022, the central party which does not include the Westminster Parliament group had total income of £4.5m during the 12 months to December 31, 2021. Total fixed assets stood at £856,348, and there were a total of 27 employees.

Some organisations that are not legally required to be audited choose to do so anyway, usually to satisfy their own stakeholders and ensure they are in accordance with regulations. However, the UK agency in charge of election finances has a different set of rules for political parties.

The Electoral Commission states that all party treasurers are responsible for compliance with financial controls set out under the Political Parties Elections and Referendums Act 2000 (PPERA). Those who fail to comply put themselves and their party at risk of civil or criminal sanctions.

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The Electoral Commission dictates that parties with annual income or expenditure of more than £250,000 must file their accounts with the commission within six months and seven days of the end of their financial year. For the SNP's year-end on December 31, this translates to a deadline of July 7 in the following year.

All accounts from parties in the £250,000-plus category must be accompanied by an independent auditor's certificate.

Audits for UK companies are typically scheduled for three months from beginning to end. This generally includes four weeks of planning; four weeks of "field work" to verify things such as the physical existence of assets that are listed on paper; and four weeks for compiling the report.

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There are a variety of reasons why an organisation and its auditor will part ways, which could include the inability to agree a fee or a conflict of interest. Some companies have a policy of appointing new auditors after the incumbent has been in place for a set number of years.

Auditors may also choose to leave due to a lack of cooperation from their client, such as withholding information that could have a material impact on the organisation's accounts. Reputational impact can also come into play.