What is required for one spouse to sign an offer on behalf of an unavailable spouse?

For one spouse to sign an offer on behalf of an unavailable spouse, written, notarized authorization from the unavailable spouse is essential. This requirement is rooted in the legal principle that one person cannot bind another to a contract without proper authorization. A written, notarized authorization ensures that the absent spouse's intent is clearly documented and legally recognized. Notarization adds a layer of authenticity and protects against potential disputes regarding whether the spouse truly consented to the transaction.

The other options do not meet the necessary legal standards. A verbal agreement lacks the formality needed to demonstrate consent and is not usually recognized in legal situations where binding contracts are concerned. Similarly, while a power of attorney is also a valid means to grant authority, it has specific requirements and is broader in scope, typically giving the agent authority over a variety of decisions, not just real estate transactions. Additionally, requiring consent from both spouses in person would not be feasible if one spouse is unavailable, which is the premise of the question. Thus, written, notarized authorization is the most appropriate and legally sound method for allowing one spouse to act on behalf of the other in transactions.