When will HBO's Game of Thrones catch up with the books?

Now that season 5 has come to a close, how close are we to the books?

Let’s say Martin drops dead tomorrow. Next season, will we need to bother avoiding book spoilers, or is the show now fully caught up and/or passed the books?

Also, the closing scene with Jon……getting Caesar’ed……was that in the books? Either way don’t tell me anything that happens after, of course.

All the stories being told on the show are up to or even passed the books. There are things that happened in the book that have not happened on the show and may come up. And many things are the same but different. Like watching an alternate universe GoT. Yes that was in the books. In fact, that is where the books end.