For the most part, companies must prepare a set of financial statements at least once per year.

However, publicly traded companies, which means companies that have their shares available for the public to invest in, need to report more frequently to ensure current and potential investors have up to date visibility on the company's financial position and performance.

How frequently publicly traded companies need to report differs by jurisdiction.

For example, public companies in the US need to file quarterly reports called 10-Qs with the Securities and Exchange Commission.

UK companies file their accounts with company's house and European companies with the relevant national business register.

If the companies are listed, they also have to publish interim reports, which are semi-annual covering the first six months of their fiscal year.

These quarterly or semi-annual reports contain less detailed information than annual reports, but are still very useful sources of information.

It is worth noting that companies can choose their own year-end date, and it doesn't have to be December 31st.

The year end date a company chooses sets its fiscal or financial year to end at that point.

For example, Microsoft's fiscal year ends on June 30th, so it'll file an annual report in the US called a 10-K for the fiscal year ended 30th of June each year.

There are many reasons why companies may choose a fiscal year different to the calendar year, including to better align their reporting with their operating cycle, or to avoid having to produce financial statements during their busiest operating period.

But once chosen, the company must stick to that reporting period and inform regulators of any changes.