Kari, you can implement preferential pricing programs for a particular group of customers (those referred by this builder, for example). However, there are risks associated with that. You will want study the potential effect of providing preferential pricing to this group of customers. Will there be a disparate impact on a protected class of customers? What is the business purpose for doing this? Is the potential reqard worth the risk? You will want to build special monitoring procedures to determine whether any protected classes are being harmed by the process.
The same would hold true for departing from established rates for instalment loans to match the competition. Is a protected class adversely affected by this practice? How will you measure that?
Differential pricing is not discriminatory per se. But you do need to take extra steps that the price differences are not applied in a discriminatory fashion.
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The opinions expressed here are personal and do not represent opinions of my employer.