Apple really wants you to purchase one of its latest iPhone models, so much so that you can grab up to an extra $100 when trading in an old iPhone. There are, of course, a few caveats.

The extra credit is being offered for a limited time through Apple's GiveBack program and will take the form of an Apple Store Gift Card. In order to receive more in return for your old handset, you have to upgrade to the iPhone XR or iPhone XS. The amount of credit offered depends on the model of iPhone being traded.

Here's the full rundown of credit available from Apple:

As you can see, the full $100 extra credit is only being offered in return for an iPhone 6 Plus, 6S, and 6S Plus. The iPhone 6 and iPhone 7 get you $75, the iPhone 7 Plus only $50, and the iPhone 8 a mere $25. If you were intent on buying a new smartphone anyway, the extra credit still helps regardless of the amount. Keep in mind that the trade value will also vary based on condition.

If you decide to trade in your old iPhone, Apple will show you how to safely backup your data and wipe the phone. Once received, Apple will either refurbish and resell it to someone else, or if it's in bad shape the materials will be recycled.

Apple isn't known for its generosity when it comes to sales or discounts in general, so the offer of an extra $100 credit is sure to be very popular. It will also have the desired effect for Apple: higher iPhone XR and iPhone XS sales at a time when smartphone sales are struggling to maintain growth.