Q: I rented a house for $6,000/month. I later realized that I was swindled and comparable rentals in the area are worth about $4,000/month. Can I claim ona’ah and demand a refund or annul the rental?

A: The rules of ona’ah apply not only to sales, but also to rentals, since rentals are considered a “sale” for that day or month. However, the Gemara (B.M. 56a,b) derives from verses that the rules of ona’ah apply only to movable items that have intrinsic value. This excludes real estate, which is not movable; slaves, which are juxtaposed to real estate; and loan documents, which serve as proof but do not have intrinsic value. Therefore, since the house is real estate, you cannot claim ona’ah on the house rental (227:29).

If the price differential reaches double the actual worth (i.e. if comparable houses go for $3,000/month), the Rama rules that there is an ona’ah claim (See SM”A 227:49).

Although the Gemara excludes real estate, slaves, and loan documents from claiming ona’ah, many Rishonim maintain that there still exists a prohibition against knowingly swindling the other party who is unaware of the going rate (see SM”A 227:51 and Pischei Teshuva 227:21).