Due diligence in tax matters becomes necessary in process of acquisition and merger of companies and/or when it is evident to analyze and diagnose  tax risk profile of company; this process seeks to inform acquirer and in general, whoever is part of  business processes what are  conditions and characteristics of the company in terms of compliance with formal obligations, filing of tax returns for income, VAT, Industry and Commerce tax, credit balances, requests for refunds or compensation, tax losses, excess of presumptive income, among others.