The great Bette Davis is under-used in this underrated haunted house vehicle, which is infinitely superior to anything in the entire "Amityville" series.
Reed and Black are a couple who house-sit for the summer at a country mansion, only to discover that (yep) the house is alive. Bette Davis is along as the aunt. Reed keeps seeing a creepy chauffeur that he remembers from a childhood funeral, while Black spends too much time talking to an old lady who lives upstairs, but that no one else in the family ever sees.
Released around the same time that Stephen King's book "The Shining" came out, this appears to borrow quite a bit from that original work, so it has many similarities to the Kubrick film released five years later, particularly its last frame. It's a bit unique as a haunted house film, since most of the horror happens during the daytime. The casting is a bit over the top. Reed seems much too melodramatic as a dull middle-class husband, and Black is her usual horror-movie self.
A fun little movie if you like your horror films paced slow, "Burnt Offerings" was directed by Dan Curtis, a veteran of the "Dark Shadows" TV series who also made some excellent TV movies based on the Frankenstein and Dracula legends.