We frequently hear that a listing, or a particular county's tax information, is not showing current data. 

All tax data is a "push" from the local jurisdictions to data aggregators such as CoreLogic. This means that CoreLogic must wait for the jurisdiction to release the tax information to them.  Transactional data is pushed out on a continuous basis throughout the year by most jurisdictions (monthly or every few weeks).  Annual assessment and subdivision data is typically pushed out only once per year by the jurisdictions.

For both transactional and assessment data, CoreLogic must await the data to be pushed out from each jurisdiction. Typically, CoreLogic has a general idea when each jurisdiction will push the data, and they schedule resources in anticipation of these data pushes. Once received, CoreLogic loads and tests the data, then releases it in Matrix and Realist as soon as possible for MLS users.

ETA information cannot be ascertained for release dates but data currency information can be found in the top right corner of any Matrix public record.