Legal Question in Real Estate Law in California

The formal property description, which most people can not understand because it is overly technical, is the legal description of what the property is, but the APN is the "common name" much as the street address of a house is. The APN merely tells you what designation has been given to the land by the County Assessor and has no legally binding effect but it what everyone uses to describe what the property is. You can not change the APN numbers because they were not created by you and they are used by the Assessor and Tax Collector and everyone else to identify the property. It is as though you were trying to change someone else's name. The only reason to switch APN numbers would be to mislead someone and that is illegal.

Why would you want to switch the APN's?

It is a really bad idea. That is how the assessor's office determines change of ownership for property tax information. Changing the APN's is going to cause the tax records for that county to become confused, and eventually a property owner is not going to receive a tax statement. Then your property is going to go into tax default, and you will end up with a whole world of problems.

APN means "assessor's parcel number" and these numbers are used to assess and bill property taxes to the correct owner when property changes hands. They are also used to guide the indexing of documents at the recorder's office. Switching the numbers intentionally and then recording the documents with deliberately incorrect numbers would be a crime (recording or notarizing a false instrument) possibly punishable as a felony. See e.g. Penal Code section 115.5, subparts (a) and (b).

You got great answers to your second question, which is that you can't change the number the assessor assigns your property, since it is their number, not yours, and it would be a crime to knowingly put the wrong APN on a deed. I write to answer your first question more directly than it has been. The answer is "yes" the APN is of no legal relevance in court unless it is a proceeding involving the assessor's office and the property. Otherwise the legal description is the legally binding identification of the property.