Many people are taking advantage of the very generous tax incentives still available to non-residents who decide to relocate to Portugal. Coupled with the modern trend for small businesses to be extremely mobile, able to relocate to anywhere around the globe almost at a moments notice, has had something of a mushroom affect, with many now starting a business in Portugal, particularly in major cities such as Lisbon and Porto.
English-speakers would be well advised to to hire a professional to manage their business accounting and tax affairs. This person will normally handle registration of the business with the relevant government agencies and then manage ongoing fiscal obligations.
Below is some initial information that you can use to orientate yourself to the requirements that you will be most concerned with when starting a business in Portugal: