Introducing a Commercial Off-The-Shelf Software Solution


Cover: Introducing a Commercial Off-The-Shelf Software Solution

Published: 28 March 2019


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Like many tax agencies, the Finnish Tax Administration (Tax Finland) built its own tax administration software from scratch. This software included around two hundred different individual software applications, all highly integrated with each other. As the whole system of applications grew larger, it became more and more expensive to maintain and slower and slower to change.

Following detailed market research and after thorough consideration, Tax Finland decided to replace its legacy software systems with a commercial off-the-shelf (COTS) product. The implementation of the COTS solution for Tax Finland in all its phases took approximately ten years. The goal of this handbook is to share Tax Finland's experiences and lessons learnt during the implementation process and to provide advice and recommendations for consideration when purchasing, implementing and maintaining a COTS product. Some of the principles presented are also suitable for the development and implementation of other types of software solution in addition to COTS.

This handbook provides background and advice on:

  • the procurement process, including the selection criteria, the drafting of the request for proposals and the contract and specialist inputs required;
  • the planning processes needed for a COTS transformation project, including the project scope, scheduling and resourcing, business preparation and change management;
  • implementation considerations including system requirements, conversion between systems, user interfaces, testing, training and the between systems; and
  • the core elements of maintenance and production support.


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