Definition: Cross-selling is the sale of complementary or related products to an existing customer (Cross-selling, up-selling, additional sales, complete sales, supplementary sales). It fulfills additional needs the original product does not cover. Example: After closing an auto insurance policy, a broker also offers accident coverage for passengers - relevant and complementary.

Psychological lever: Cross-selling works best once trust is established. A satisfied banking client who has just signed for a loan is more inclined to add a matching insurance policy because they see the benefit and trust the advisor. The principle of reciprocity comes into play: having already received value (a good offer, helpful advice), the customer is receptive to further suggestions.

Smart application

• Ensure relevance – Offer only products that truly match the customer’s needs. Unwanted cross-sells feel pushy and can erode trust (What is Cross Selling?| Shopify). 

• Mind the timing – Cross-sell only after the main purchase decision is settled. Additional offers during deliberation may overwhelm the customer.

• Communicate added value – Use clear benefit-oriented language: “With [Product B] you protect [Product A] optimally and save money long-term.”

Tip: Cross-selling is a growth engine in many industries - raising revenue per customer without acquiring new ones.
Non-intuitive fact: Studies (Harvard Business Review) show cross-selling can even create losses with certain “problem customers,” e.g., when add-ons trigger excessive support costs. Therefore, professionals qualify which customers are suited for cross-selling. Used correctly, it strengthens loyalty because customers feel comprehensively served from a single source.