When you need to include a line break within a textbox in SQL Server Reporting Services, a predefined Visual Basic constant may be used.  The vbcrlf, Visual Basic Carriage Return Line Feed, handles this quite nicely within an SSRS expression.  For example:

…will look like this when rendered:  

An advantage to using the vbcrlf within an expression is you can leave the text all in one textbox.  That means not having to worry about aligning two textboxes & removing padding from the top and bottom of both.  Word wrapping issues between textboxes are also eliminated.

For more information, see Constants Declared by Visual Basic.