Solution : https://service.sap.com/sap/support/notes/813490 (SAP Service marketplace login required)
Key words : 
maintain tax rates, brazilian tax calculation, enter tax rates, overlapping periods, /3 system configured, program error, support package, advance correction, corection instructions, note 670681
Related Notes : 
       
| 670681 | Brazil: Validity of tax rates maintained inconsistent |