It's perfectly legal for you to take out a mortgage solo, even if you're married. The lender, however, may still want your spouse to sign off on the mortgage. Even if he's not on the hook for the loan, having him sign the paperwork protects the company's lien on your house. It is also crucial that a spouse know about the loan, even if he or she is not on the mortgage.
In general, the spouse must sign a deed of trust, the Truth in Lending and Right to Cancel documents. By signing these documents, they are simply acknowledging the existence of the mortgage.
Even if you take out a mortgage without your spouse, the lender may want him to sign some of the paperwork in order to protect the lender's lien on your house and ensure he's at least knowledgeable the loan exists.
Note vs Mortgage
The mortgage is actually two documents, not one. Signing the promissory note commits you to pay back all that money you borrowed. The mortgage or deed of trust says that if you don't, the lender can foreclose on the house.
If your spouse isn't your co-buyer, she doesn't have to sign the note, but the lender may insist she sign the mortgage. That ensures the lender's claim on the property trumps any marital rights she has to the house.
Community Property and Home Ownership
In community property states, if you buy the house after you marry, your spouse automatically owns half of it, unless your prenup rules that out. A few states still have dower laws, giving a widow a claim on the property, but these anachronistic laws do not recognize modern situations such as same-sex marriage. Michigan abolished its dower law in 2017 for that reason.
The last thing your lender wants is to have someone else with a legal claim that could take priority over the mortgage lien. Having your spouse sign the mortgage eliminates that as an issue.
Good News About Your Credit
If you're concerned about your spouse's credit dragging down your loan application, don't worry: Her signing the mortgage won't make that happen. As long as you have the money and credit score to go it alone, you can apply by yourself and keep your spouse's financial history off-stage. That doesn't prevent your spouse sharing title to the house, as long as the deed names you both as the new property owners.
Implications for Your Spouse
Whether or not your spouse signs the mortgage, he's not liable for the debt if his name's not on the note as well. If the house is 100 percent yours and yours alone – you have a prenup clearly separating your finances, or you bought it with an inheritance that's your separate property – he doesn't have a legal claim to the house. In that case, your lender may not care whether he signs.