Does my spouse have to get independent legal advice before guaranteeing my business loan?

Not as a strict universal legal requirement in every single case, but most commercial lenders insist on it as a practical condition before they will rely on a spouse's guarantee, so in practice it is very common. Independent legal advice, usually confirmed through a signed certificate from a lawyer who did not act for the borrower, protects the lender against a later argument that the guarantee should be set aside because the spouse was subject to undue influence or did not properly understand what they were signing.

Because that kind of challenge is a real risk to a lender's ability to enforce a guarantee, many lenders simply will not accept a spousal guarantee without proof that independent advice was obtained first. Even in situations where a lender does not specifically require it, a spouse being asked to personally guarantee a business loan, with real exposure to their own assets if the business fails, should still get independent legal advice, since the point of that advice is to protect the spouse, not just satisfy the lender's paperwork.