This time last year, Apple was preparing to offer out-of-warranty iPhone battery replacements for just $29 compared to the usual price of $79. The offer would last a year and applies to the iPhone 6, 6 Plus, 6s, 6s Plus, SE, 7, or 7 Plus models. We're now almost a year on from that date, which means there's just three weeks left to take advantage of the offer.

Apple would love for you to buy an iPhone XS, iPhone XS Max, or an iPhone XR instead of replacing your existing iPhone battery. There's even an incentive to do so in the form of up to an extra $100 for trading in your old iPhone. But it's nearly Christmas and money needs to be spent on other things, so a battery replacement makes more sense for a lot of people.

There's two ways to get your iPhone battery replaced: visit an Apple Store or mail in your iPhone. The Apple Store visit is the quicker of the two options, simply make an appointment at a Genius Bar via Apple's website or support app and then visit for a same-day repair. Alternatively, visit Apple's website and get a mail-order box for your iPhone. This method means you'll be without a smartphone for 3-5 business days and costs an extra $6.95 for shipping.

Apple officially states that 80 percent battery degradation is required for the $29 replacement to be carried out. However, as Business Insider points out, if you're close to that, for example, 83 percent, then the Genius Bar will likely still offer to do the replacement. If you aren't sure, make the appointment and see what happens. You'll probably leave the store with a new battery.

If you have an iPhone that's an older model than the iPhone 6, don't worry, it's still possible to get a $29 battery replacement through iFixit. You'll have to carry out the battery replacement yourself, but the models included in the offer extend to the iPhone 4s, 5, 5s, and 5c.

This article originally appeared on PCMag.com.