>>I have an SSRS report with a table that shows two numeric columns and the difference between them
>>I'm using the report builder that comes with VS 2013. It's a local report associated with a Winform app.
>>I wanted to sum the differences and couldn't see a straightforward way to sum an expression.
>>
>>I found some convoluted solutions on the web but decided instead to add a computed column to the dataset and used that.
>>
>>Is there a better way?
>
>You could also sum differences this way...
>
>SUM( Fields!Value1.Value) - SUM( Fields!Value2.Value)


I had worked around the issue by adding a column to the dataset, but I tried out both your suggestions and both worked as you said they would.
I'll put that away for future reference, thanks