Technically, a sole proprietorship cannot be converted to a company. A sole proprietorship is a separate legal entity from a company and the law does not provide any process for conversion.
Instead, what needs to be done is to terminate the sole proprietorship, inform ACRA that you have ceased to carry on business as a sole proprietorship and incorporate a new company. In that case you may need: (i) to transfer the business assets that will be used in the business and any existing contracts over to the new business structure; and (ii) to get new licenses or permits (as licenses and permits usually cannot be transferred). You should seek the advice of the agency issuing the licenses or permits on their validity and seek professional advice generally if you are uncertain as to what should be done.
At the point of submission of the online transaction to incorporate the company, you may indicate in the online form that the company is going to take over the business of the registered business (that is, the sole proprietorship). You are required to provide the details of the registered business (that is, the sole proprietorship) as well as the date of termination of the business (which can be postdated up to 3 months).
Thereafter you will have to submit an online transaction to terminate the business registration (that is, notify ACRA that you have ceased to carry on business). The fee payable is $20. The fee payable to incorporate the new company is $315.
Please check the ACRA website for more details.