The essence of a MNC is that they bring inward investment to countries that are not their home base. If they choose to expand by building production facilities they will be bringing in inward investment into the country. This investment is likely to provide a boost, not only to the local economy but also the national economy.
Building a new plant requires resources - land, labour and capital. Labour has to be found to help construct the plant and all the equipment that goes into it and some firm somewhere will be hired to build the machinery and equipment, provide the bricks, steel, cement, glass etc. that go into the building. If it is announced that Company X from Germany are to build a new distribution centre in the UK at a cost of £10 million, this effectively means that a whole host of firms will be getting additional work to the value of £10 million. It can also be expected that the additional income will find its way through the local economy. If additional people are hired, they will receive an income which they spend. Inward investment therefore can act as a trigger to generating wealth in the local economy. If a MNC is attracted to an area then this might also lead to other smaller firms in the supply chain deciding to locate in those areas. Other firms providing services to these firms are then attracted to the area and so on.