One of the fundamental The Points Guy principles is to click through a shopping portal before making any online purchase, whether its buying clothing or booking hotels. For years, online shoppers had to decide between earning miles through an airline shopping portal or earning cash back through a cash-back portal.In February 2019, Rakuten — formerly known as Ebates — shook up the market. Instead of limiting members to only earning cash back, new members could elect to earn American Express Membership Rewards points when they signed up for a new account through a special landing page.As of today, Oct. 30, Rakuten and American Express are expanding this partnership to allow all existing accounts to opt into earning Amex Membership Rewards points instead of cash back.To be eligible, you’ll need to be a U.S. American Express card member with a card enrolled in the Membership Rewards program. To opt in, you’ll need to link that card to a new or existing Rakuten account and select in your account settings to earn Membership Rewards points.Back in February, this new earning opportunity was good enough for a number of existing Rakuten members to abandon their old accounts and sign up for a new account, and I was one of them. While earning cash back is great, the ability to earn Membership Rewards points — which TPG values at 2 cents each — instead of cash back meant I was doubling my return.In discussing this expanded partnership with Rakuten, I asked if members like me will be able to combine duplicate accounts. Unfortunately, the answer is no. So, if you set up a new MR-earning account since February, you won’t be able to merge that account into an existing account.Rakuten also confirmed that members that have an accumulated balance in their non-Membership Rewards earning account won’t be able to convert that balance to Membership Rewards. Members will be able to opt into earning MR points on future transactions, but any accumulated cash back earnings will pay out by PayPal or check – based on your current earning preference.If you’re unfamiliar with Rakuten, now’s a good time to learn about this way of double-dipping on the earnings from your online shopping. Members earn cash back or Amex Membership Rewards points for making a purchases online at one of over 3,500 online retailers after clicking through a Rakuten affiliate link.The earnings rate depends on the merchant and whether or not Rakuten is running a promotion. We’ve written about Rakuten a few times during especially good deals — such as:Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.Earn up to 20% cash back or 15 Amex points per dollar shopping online at hundreds of retailersEarn 12x Amex Membership Rewards points on hotel bookingsEarn 10x Amex points per dollar shopping at big name retailersEarn 5% back (or 5x Amex MR) at restaurants through Rakuten DiningAt the end of each calendar quarter, members get paid their accumulated earnings for the quarter — by check for those that earn cash back or by automatic transfer to Membership Rewards for those who’ve elected to earn points. Note that you’ll need to have earned at least $5 or 500 points to get a payout. Otherwise, your balance will roll forward to the next quarter.If you want to make sure not to miss out on earning points, miles or cash back on future purchases, Rakuten and a number of airline shopping portals — including Alaska, American Airlines, Southwest and United — have browser extensions. You can install these in certain browsers to be reminded to use the portal whenever you’re shopping at a participating retailer website.