SQL Server has three ways to handle MAX data types: IN_ROW_DATA, ROW_OVERFLOW_DATA, and LOB_DATA. If you use data compression—say page compression—it =can= compress anything stored in the IN_ROW_DATA region because the page data compression algorithm only functions against IN_ROW_DATA. But that's probably only a very small percentage of data stored in a MAX data type. You can use the following query to see how much data is in each of the three regions for a MAX data type.