Here is the official link to send employers about extension letter:

[MadMax101 32]

It's in chapter 7.1 of the Handbook for Employers M-274. However, you must be able to also provide a type B document like a Driver's License or ID card as the Extension letter turns your green card into a type C Document.

https://www.uscis.gov/i-9-central/71-lawful-permanent-residents-lpr

 

Key sections:

Employees must be allowed to choose which document(s) they will present from the Lists of Acceptable Documents. You cannot specify which document(s) an employee must present. Employees who attest to being an LPR in Section 1 may choose to present a List A document (such as a Permanent Resident Card, Form I-551) or a List B and List C document combination (such as a state-issued driver’s license and unrestricted Social Security card). If the employee presents a List A document, do not ask or require the employee to present List B and List C documents. If an employee presents List B and List C documents, do not ask or require the employee to present a List A document.

 

 

• The combination of an expired Permanent Resident Card and a Form I-797, Notice of Action, that indicates that the card is valid for an additional year, is an acceptable List C evidence of employment authorization for one year as indicated on Form I-797. At the end of the one-year period, you must reverify.

[Unidentified 2,930]

Yes, this is for when you have been accepted for a job and they ask you to prove that you are able to work in the US. However, if you have already worked for them for a while and your Green Card has expired they may not ask you for evidence that it has been renewed as it's only the card not your legal status that has expired. At least that's what I've been told. 

[charmander 692]

This is a good reference in the sense that one can no longer claim the expired card plus the extension letter suffice I-9. You'd at least need a valid driver's license as a List B evidence.

 

The I-551 stamp part is vaguely described though. It is not clear if it would serve as a List A or List C document.

 

 

[MadMax101 32]

2 hours ago, charmander said:

This is a good reference in the sense that one can no longer claim the expired card plus the extension letter suffice I-9. You'd at least need a valid driver's license as a List B evidence.

 

The I-551 stamp part is vaguely described though. It is not clear if it would serve as a List A or List C document.

 

 

The Stamp seems pretty clearly explained in chapter 13 as type A. It's just not easy to get an appointment if you find out you need it. The office in our city hasn't had any appointments available for booking all week and the next city over doesn't have an opening for a couple weeks. 

1. Foreign passport that contains a temporary I-551 stamp or temporary I-551 printed notation on a machine-readable immigrant visa (MRIV)