I think you get get it from the RequestContext.RouteData.Values["tag"].  Try that,  I am not for sure but it should.

That doesn't work atleast in my case when I used following statement in the view:

Parent View:

@{ Html.RenderContentData(content, false, "Card"); } //"Card" is tag that should be used to resolve render

[TeplateDescriptor(Tags=new []{"Card", "Line") ...]

MyController: ContentControler<MyContentType>{

public Action Result(MyContentType currentContent){

//... I want to switch actual view by current active tag

  
}
}

I've looked at decompiled code of RenderContentData method, and found out that it uses tag value passed only to resolve template. It doesn't put it anywhere.

So I assume that there is no out of the box way to do that.

You can listen on:

public event EventHandler<TemplateResolverEventArgs> TemplateResolved;

then store in somewhere by self and reuse it after!

Hope that help!

Ha Bui