As credit card sales account for an ever-greater share of consumer spending, retailers need to be increasingly conscious of how the associated fees impact their bottom lines.

As of this spring, Visa and Mastercard will take an even bigger bite of profits, according to a Wall Street Journal report citing people familiar with the matter.

The payments companies — which as of mid-2018 had together issued nearly 6 billion cards worldwide — plan to raise certain existing fees in April, per the sources, which would place a greater burden on retailers to increase prices, since most don’t have wide enough margins to eat the cost themselves.

According to the National Retail Federation, banks take an average of 2 percent in fees for every credit card transaction, though this share can go up to 4 percent for some premium rewards cards. In total, swipe fees average about $80 billion a year nationwide.

The new Mastercard fees would also reportedly make returns costlier for merchants, who would not be reimbursed for that portion of the transaction in certain cases. This could hit online retailers particularly hard, since they tend to see return rates of 15 to 30 percent (and even higher in apparel and footwear), versus 9 percent for traditional brick-and-mortar stores.

Credit card fees have been the subject of several court battles in recent years: in June, the Supreme Court ruled that American Express was within its rights to include “anti-steering” clauses in its contracts to prevent businesses from encouraging shoppers to use lower-fee cards like those issued by Visa, Mastercard and Discover. (Amex’s rewards program makes it among the highest-fee networks.)

In September, Visa, Mastercard and several U.S. financial institutions agreed to a $6.2 billion settlement on a class-action lawsuit alleging that the card networks and banks colluded to keep fees high for their own benefit. Separately, a group of large retailers, including Amazon, Target and Home Depot, are suing Visa and Mastercard for the right to reject certain cards due to high-swipe fees.