Why is my MacBook Air not eligible for AppleCare?

That's a hard one to guess.

You may use site to check:

• Check Your Service and Support Coverage - Apple Support

https://checkcoverage.apple.com/

"Enter your product serial number"

Review your Apple warranty status and eligibility

to purchase additional AppleCare coverage.

Details about 'Buy an AppleCare plan' are

in the above left-side article, on this topic

• Correct the purchase date or expiration date for your AppleCare agreement - Apple Support

https://support.apple.com/en-us/HT202696

(Above, lengthy article, includes If your coverage expiration date is incorrect

and offers self-help to correct those matters by updating Apple records, & etc.)

muguy:

Thought those details were already covered adequately

and perhaps also read/understood; but I could be wrong.

"Details about 'Buy an AppleCare plan' are

in the above left-side article, on this topic"

Any reference to 'time and space' needs a clarifying element.

Some resellers who are not official Apple, offer a different kind

of limited warranty & end user experience, that has other rules.

A friend who bought an 2008 iMac, from Best Buy in Anchorage

and their warranty; which failed to cover a known graphics issue.

Essentially, she had an expensive 'new' failure she could not afford;

and that let her shelve the functionally dead Mac. And she so went

back to less expensive, disposable PCs and WindowsOS.

An in-house extended warranty may (or not) have been available

from Best Buy; that is not an official AppleCare product. I have not

followed their marketing; or final conclusion of the sad story here.

But know it matters if you are going to invest, make it all Apple.

Best buy here, did not tell her of timely option to get AppleCare.

As a university graduate who took additional courses in science

& technology; their mentorship did not suggest how to shop.

The online Apple support and sale, has significant details with

legal-side warranty information, and in-store help too. (Sorry.)

Call Apple support directly and have available the date of purchase and location

and serial number of the Mac. Also, have the Mac powered on, sign into your Apple ID,

and be on a network.

I had a similar issue when I first bought my M1 MacBook Air and called Apple Support

and after a short discussion and transferred to a sales person I purchased AppleCare+.

It took about 15 minutes in all.

You can typically add Apple Care within 60 days of purchase. https://www.apple.com/support/products/mac/