With rising mortgage interest rates, consumers looking for the best deal on mortgages or other settlement services are often turning to comparison-shopping platforms and mobile apps.

The CFPB on Tuesday issued an advisory opinion that it says aims to protect Americans from “double-dealing” on digital mortgage comparison-shopping platforms, stating that financial arrangements that influence or manipulate search results are illegal.

Companies operating these digital platforms appear to shoppers as if they provide objective lender comparisons, but may illegally refer people to only those lenders paying referral fees, the advisory opinion states.

The advisory opinion seeks to assist law-abiding companies to comply with existing law, and does not create any new requirements, but rather offers clarity on how firms can navigate issues associated with digital mortgage comparison-shopping platforms, according to the CFPB.

The advisory opinion also describes how companies may violate RESPA, and potentially other laws, if they coerce payments from mortgage professionals, unlawfully steer consumers, or engage in other illegal referral activities. Illegal referral activities may include presenting one or more service providers in a non-neutral way or biasing the platform’s internal formula to favor preferred providers.