A personal account is for your own personal use to pay expenses and bills that are your own. A business account allows you to ring-fence money that belongs to your business. Keeping accurate financial records is a regulation of running a business, especially limited companies. As a director, you have the responsibility to do all you can to keep the business solvent and in profit. A business account, free or otherwise, also shows professionalism and is often a requirement for loans and investors too.