How long is a reentry permit valid for with a pending I-829?

Generally, the reentry permit can be as much as two years from the date of issuance.

A reentry permit will most likely be granted up to the period of validity of the extension granted while the I-829 is pending. It is unlikely that a reentry permit will be granted for the full two year period a reentry permit is generally valid.

Permission to return to a permanent residence in the United States requires identification of the applicant's permanent residence. Therefore, if the application to remove the condition, Form I-829, from the permanent resident status is denied, the applicant would no longer have a lawful permanent residence in the United States. Therefore, the validity of the permission to return would become invalid if and when the Form I-829 would have been denied.

It will depend on the reasons given for the reentry.

A U.S. reentry permit is valid for a two-year period and may be renewed for an additional two-year period. Yes, someone who is a conditional lawful permanent resident would be eligible for a U.S. reentry permit.

A reentry permit is issued in two year increments and may be renewed if needed. While the investor is maintaining lawful conditional permanent residence, he may file for and be granted the reentry permit to preserve his permanent resident intent in the United States while he stays abroad at lengths.

Generally two years unless you have already been overseas with a green card for more than four years.

A reentry permit normally is valid for up to two years. Conditional lawful permanent residents may apply for and receive a two-year reentry permit.

If the I-829 is pending more than one year, the investor can go to the local USCIS office, make an Infopass appointment, and obtain a stamp in the passport. He would have to continue to do this according to the validity periods of these stamps.

Ordinarily, the reentry permit will only be approved up until the period of validity of the green card, or the extension granted by virtue of the I-829 filing. It is unlikely the reentry permit will be granted for the full two-year period.