Address validation performed in a GetTax request are said to be "implicit" as opposed to "explicit" as performed in a Validate request. See documentation here for more detail: http://developer.avalara.com/api-docs/designing-your-integration/address-validation
In a GetTax request, normalized addresses are not returned as they are in a Validate request - and therefore follow a "bottom up" validation process to ensure that the address in its current state returns the highest quality tax result possible. This process is enabled when a non-validated address is passed in the Origin or Destination address objects.
The “bottom up” method essentially starts with the highest level data element (CountryCode) and works its way up the data tree [CountryCode ==> Postal Code ==> Region ==> City ==> Street address ==> other non-address data) to establish a unique jurisdiction and collect an array of jurisdiction parameters to be used to perform the tax calculation. As stated above however, a Normalized address does not replace the provided address and will show up as such in reporting.
The GetTax method does not return a normalized address as part of the documenting process. Addresses via the provided via GetTax request are used throughout the document process. Only a Validate method will return either a normalized address or an error / exception with reasons for the failure.