I'm very new to Solidworks so this might be a simple problem on my part. What I want to do is mirror the tab shown below about the 'Right Plane' so I have an identical tab on the opposite side of the part. However see the screenshots below. Clearly this is not a mirror of the original tab. It looks like it is extruding the new tab to the same face the original was extruded to?
How do I mirror just the tab? Attached is the file.
Not sure why SolidWorks does not like what you did but you extruded the tab up to surface so when you mirror the tab, it extrudes out to the same surface. To see this for yourself change up to surface to blind.
To fix I would recommend moving the tab extrude above the first mirror. To do this you will need to fix two relations in your tab sketch: Coincident0 and Coincident1 are created from geometry from your first mirror. After you fix the relations, you can move the tab feature above the mirror feature and add it to the mirror feature.