According to International Financial Reporting Standards (“IFRS”) an accounting policy should only be change when the change is either required by a standard or interpretation or when it means that the financial statements give more relevant and reliable information about the effects of transactions, other events or conditions on the entity’s financial position, performance or cash flows. The reason I quote IFRS is because it’s the basis for most accounting standards in the world. Obviously one should consult their local legislation, but something as fundamental as changing an accounting policy is most probably treated the same way. 

Once you’ve reached to a decision that you should change the accounting policy as it is, there’s one key thing you need to ask yourself. “How does this effect my financial statements for prior and current period?” Note here that changing an accounting policy isn’t a change in estimates that’s never adjusted retrospectively. On some cases changes in accounting policies are actually required to be taken back to prior periods so that all the prior period accounts are accounted using this new method. It can also be that no retrospective treatment is required. Whether it’s one way or another is mostly either stated in this very same policy you’re applying or in the fundamental policies about changes.

One way or the other, make sure you know exactly what you’re doing before bluntly deciding on a change and going onwards with it.