I'm Doug, and I'm sorry to hear of the confusion. My goal is to provide you with excellent service today.
In direct answer to your question, the CA anti-deficiency statute only applies to a lender who forecloses on the property through a Deed of Trust. If that is what happens to your relative in the event of a default, then both you and they will be protected by the anti-deficiency statute in CA so long as the loan was a purchase money loan to buy the property originally.
However, the lender has another option and while not used often with just a borrower, if there is a co-signor who has assets the lender may instead of foreclosing outside of court, may choose to sue in court for foreclosure rather than take the property through the deed of trust---and in so doing, get a deficiency judgment against you.
I'll preface my remarks by saying I am fully against the idea of anyone co-signing for someone else who is not at a minimum a family member by blood or marriage---and then to do so only if you can afford the monetary loss.
With nearly 30 years of legal practice under my belt and countless conversations with folks seeking bankruptcy protection because of a loan that they co-signed on a decade earlier, and is being sued on---I have to suggest that agreeing to cosign carries a real risk.
As a co-signor, you have absolutely no interest in the transaction or the property. You are merely acting as a guarantor---as a bank---ready to step forward and pay out of your own pocket, if the loan payments are not paid.
As a co-signor, the lender can let the owner keep the property if they default and just come after you. The fact that there might be equity in the property today means little in terms of protecting you years from now. If there is a default, both of you could be sued. And with people who need a co-signor to begin with---when it comes time to pay the judgment it is the co-signor who is usually able to pay, and gets hit the hardest.
You gain no lien right as a co-signor. Your only remedy would be to sue them for breach of contract---presuming that you can show that they agreed with you, that as consideration for you co-signing, that they promise to male all the payments.
Your remedy is to sue someone who probably might well turn out to be a judgment proof defendant, as they couldn't pay the mortgage in the first place---much less a large money judgment, and a person who can avoid the loss entirely by simply filing bankruptcy.
In a word----don't do it, unless you can afford to take the entire loss yourself. And if you can, you might just as well make the loan yourself---because at least you could take a promissory note.
If you must agree to co-sign for the sake of your relationship with the other person---then demand to be on the title as well, so at least you can compel the sale of the property through court if they default and place the property at risk of foreclosure and you are risk of a money judgment.
Finally, know that if you co-sign, that will impact your credit and show up as a credit debt that you owe. The effect could be that you won't qualify to purchase a car or a home on credit. And, taking on such debt can result in your credit score being lowered if they are late even one time on a mortgage payment.
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