You require a registered office in Singapore to operate either a business firm or a company there. The registration is mandatory and cannot be dispensed with under any circumstances. The advantage of registration is that once registered you can operate with any other company or concern in the world. 

You will also be required to maintain certain documents like the certificates of incorporation, other statutory records as prescribed under the local law and all records relating to your accounts in your Singapore office. Of course as Director of the organization, you or the Board of Directors have the option to keep these records at a different place.

An important aspect is that generally all your documents will be open to public inspection. However, there may be a few secret documents that are not open to public in general but to the share holders only. Under such circumstances, if you decide to keep your documents at a different place, it may mean additional expenses in terms of Singapore office rental that may be an expensive proposition. 

Documents that are open to public inspection shall include both Memorandum and Articles of Association and they should also be filed with the ACRA. While the memorandum provides general information about your business like the name, address, details of the shareholders and the Singapore office space you are utilizing while the articles will provide specific information and rules regulating the governance of your organization.