I also follow this approach. I also use these other rules:

    var something =
    [tab]someReallyLongCallThatWouldExceedMargin()

    someObject
    [tab].call()
    [tab].otherCall(param)
    [tab].yetAnother(
    [tab][tab]withLong,
    [tab][tab]parameters);

I use four literal spaces, but I think this approach would work well with literal tabs. The only problem is most IDEs do not have an expressive enough configuration to do this, nor do I think I could make it easily happen out of the box with tools like indent or gofmt.