This thesis aims to develop a maintainable solution when implementing a Business to Business payment solution. In order to prove that the solution is maintainable we will use a metric, which Deng & Mercado has constructed, for measuring how maintainable a software product is. The research is done with a company based in Malm¨o called Knowit AB. The company aims to help businesses with the digital transformation. A part of the company works with e-commerce which already has Business to Consumer payments but lacks the option for Business to Business payments. The thesis uses a mixed methodology, which means we will take both a quantitive and a qualitative stance to help us answer our research questions. The thesis has a structure where we begin with an introduction of the subject and why we have chosen to take this approach. Explanation of the different subjects that is neccessary for the reader in order to understand the result part of the thesis is in included in the preliminaries. This is followed up by a result and discussion part where we answer our research questions and discuss what our research resulted in.