Online marketplace Jet has rolled out its first holiday promotion to ring in the upcoming season.

Jet is offering 5% JetCash back on orders purchased starting Sept. 18 through Oct. 29. The earned JetCash, which are shopper credits customers can use to purchase items on Jet.com, will be available to redeem during the holiday shopping period Nov. 13-Dec. 31.

One dollar of JetCash is equivalent to one dollar off a purchase on the online marketplace. Consumers can earn a maximum of $50 JetCash.

The promotion looks to boost holiday spending on the marketplace and attract new Jet customers. For instance, JetCash will only be awarded to customers with a Jet account, meaning that customers cannot make qualifying orders using Guest Checkout.

“This effort rewards our loyal customers with some cash toward their holiday shopping and attracts new shoppers to check out Jet.com, letting them decide how and what to use their credit toward,” says Liza Landsman, president of Jet.com.

Jet.com is promoting its JetCash offer on its website.

While Jet has offered JetCash rewards to consumers in the past, this is the first time it is offering JetCash back specifically for the holidays, the company says. Jet says it will market the promotion through email, digital media, on Jet.com and via Jet’s mobile app.

Jet operates an online marketplace on which retailers and brands sell their products on Jet.com, and Jet takes a commission from the sale of each product.

Jet declined to comment on whether it will cover the price difference when customers use JetCash for marketplace merchants’ products during this promotion. However, some marketplace sellers say Jet has told them that the online marketplace will absorb the costs. That means if a customer uses $10 worth of JetCash on a $20 product, the marketplace seller will still get $20, minus the commission fee Jet takes.

If Jet covers the JetCash difference, e-retailer Christmas Central says the promotion can benefit marketplace sellers as well. “We see JetCash as a great opportunity for both customers and merchants. We are optimistic that this incentive will drive additional traffic for Christmas Central, and encourage repeat customers, both now and during the holiday season,” says a Christmas Central spokeswoman. The retailer sells on various marketplaces and its own e-commerce site.

Online holiday sales in the U.S. will increase 12.2% this season to $129 billion from $115 billion in 2016, according to Forrester Research Inc. projections.

More consumers will shop online this season, with a total number of web shoppers in the U.S. estimated at 196 million, up 3% compared with last year, Forrester says. The research firm defines the holiday season as Nov. 1 – Dec. 31.

For more on the holiday outlook and how e-retailers are preparing, listen to this episode of the Digital Commerce 360 Insights podcast.