The study sought to ascertain the magnitude of the external tax compliance costs incurred by SMEs in Ghana from the perspective of the tax professionals who provide the service. Tax professional firms were selected from the Institute of Chartered Accountants and the Chartered Institute of Taxation for the study. The study distinguished between the average annual costs for small, medium and larger firms to compute and file returns, deal with tax authorities, implement changes in tax laws, and maintain records for tax purposes on behalf of their clients. The cost was found to be regressive in nature, indicating that the burden was relatively higher for small businesses.