Anyone who flies Southwest, Delta, or United can earn major bonus miles at Apple right now, but the deal only lasts 24 hours

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Earn up to 8 miles per dollar when you make an Apple purchase online.

• Shopping portals offer an easy way to earn miles, points, or cash back on purchases you make online.
• Travel brands from American Airlines to Chase to Marriott run these portals, and you simply have to log in to your loyalty program account, search for a retailer through the portal, then click through to make your purchase.
• While some retailers routinely have high shopping portal bonuses, it's pretty rare to find a high earning rate for Apple.
• Monday, you can earn 8 American or United miles per dollar on Apple purchases, compared to the usual rate of 1 mile per dollar. This is a great opportunity to get closer to an award flight on American, United, or one of their alliance partners like British Airways or Singapore Airlines.

• Consider using a credit card like the Chase Freedom Unlimited (to maximize your points earnings) or the Platinum Card® from American Express (to get purchase protection) to make your purchase.

If you missed out on Prime Day deals like up to $29 off Apple Airpods and you have an Apple purchase to make, Monday, July 22 is the time to do it. You can currently earn 8 miles per dollar on Apple purchases made through the American Airlines and United Airlines shopping portals.

This elevated earning rate is only available on Monday, though these shopping portals have been known to offer 8x miles at Apple several times a year.

Shopping portals are a great way to maximize your online purchases by earning extra points, points, or cash back on every dollar you spend. Most airlines - along with banks like Chase, a handful of hotel brands and cash-back sites like Ebates - run these portals, and you simply have to be a loyalty program member to use them.

For example, United's shopping portal is called MileagePlus Shopping. To earn miles through it, you need to log in to the portal using your United MileagePlus loyalty program account credentials (or create one for free), navigate to the retailer you want to shop with, then click through to make a purchase.

United MileagePlus Shopping

So, in this case, you'd find the store listing for Apple, then click on the "Shop now" button. Just make sure you make your purchase in this same window; the portal awards you extra miles by using cookies to track your purchase, so if you click out of the original tab you used to navigate through the portal, you won't get those rewards.

Travel website The Points Guy values American miles at 1.4 cents apiece, so earning 8 miles per dollar would get you an 11.2% return on your spending. TPG values United miles at 1.3 cents apiece, so earning 8 United miles per dollar would get you a 10.4% return.

Other shopping portals offering bonus miles on Apple

In addition to American and United, the following airlines are offering elevated bonuses for Apple purchases today only:

• Alaska Mileage Plan: 6 miles per dollar
• Delta SkyMiles 4 miles per dollar
• Southwest Rapid Rewards: 4 points per dollar

The best option for you will likely depend on which program you have the most miles with. If you already have tens of thousands banked with Alaska and zero with American or United, for example, it probably makes more sense to go through Alaska's portal even though it's offering fewer miles per dollar. That way, your new miles will get you closer to your next award instead of starting your earning from scratch.

Which credit card to use

What makes shopping portals extra lucrative is that the points, miles, or cash back you earn through them are in addition to what you'll earn from the purchase with your credit card. So using a credit card that earns you bonus points is a great way to stack your earnings.

Most credit cards don't offer bonus rewards on purchases from big-box stores, but the Chase Freedom Unlimited could be a good option thanks to its earning rate of 1.5% cash back on all purchases. That becomes even more rewarding if you also have the Chase Sapphire Preferred Card, Chase Sapphire Reserve, or Ink Business Preferred Credit Card, because then you can combine your cash-back rewards with full Ultimate Rewards points and ultimately transfer points from the Freedom Unlimited to travel partners - including, incidentally, United.

Another good option would be a credit card that offers purchase protection, since Apple items are costly and you'll want to make sure your tech is protected. The Platinum Card from American Express is a top travel rewards credit card for many reasons, but a lesser-known one is up to $10,000 for covered incidents of loss, theft, or damage for up to 120 days from your date of purchase. See the benefit terms for more info.

Click here to learn more about the Platinum Card from American Express from Business Insider's partner The Points Guy »

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