Rakuten's biggest cash-back promotion of the year is live, and it runs through Oct. 7. The Big Stack Event has boosted rewards at a long list of retailers to 10% back, with some deals quietly hitting 15% or even 20% — including several travel names worth knowing about.

For trip planners, the standout part is the travel lineup. Expedia, Hotels.com, IHG Hotels and Resorts, Vrbo, Viator and Samsonite are all offering elevated cash back during the event. So if you're booking a hotel, a holiday rental or a tour in the next few days, clicking through Rakuten first could shave a meaningful amount off the price after the fact.

There's a twist that makes this more interesting for points collectors: Rakuten lets you swap cash back for rewards points. Instead of 10% back, you can take 10 American Express Membership Rewards points or 10 Bilt points per dollar. Depending on how you redeem them — particularly with Amex's airline and hotel transfer partners — that can be worth considerably more than the cash.

New to Rakuten? The welcome offer has also been bumped up. Sign up now and you'll get a $50 bonus after spending $50 at an eligible retailer within your first 90 days, up from the usual $30.

Beyond travel, the event covers plenty of everyday and gift shopping: Macy's, Gap, Nike, PetSmart, Sam's Club, Carter's, Crocs, Dyson, Hoka, Lego, DSW, Zappos, Land's End and Dermstore are among the participating stores — handy if you're getting an early start on holiday buying. One catch: Target is part of Rakuten but isn't offering a boosted bonus this week, even during its own Target Circle Deal Days sale. You'll still earn the standard 1% by going through the portal, so it's worth the extra click anyway.

The rewards stack further if you pay with the right card. A general cash-back card like the Citi Double Cash (2% on everything) or Amex's Blue Cash Everyday (3% at US online retailers, up to $6,000 a year) adds a second layer on top of the portal earning. Rakuten's own Amex card, which carries no annual fee, earns 4 points per dollar on top of portal rewards — which works out to 14% back during the Big Stack Event.

One last habit worth building: before you check out, check whether the merchant also has a targeted offer through Amex Offers, Chase Offers, Citi Merchant Offers or American Airlines' SimplyMiles. Stacking a merchant offer on top of a portal bonus and card earnings is where the real savings are. And since cash-back portals don't always match each other, a quick comparison before a big purchase pays off.

The clock is ticking on this one — the boosted rates and the $50 new-user bonus both end Oct. 7. Story via The Points Guy.