Co-owned property as business loan security: who signs, and what they're agreeing to

A large share of property-secured business loans involve a home owned by a couple, only one of whom runs the business. Others involve a property shared with a sibling, a parent, a business partner or a former spouse. In every case, the same rule applies: a lender wants security over the whole property, and that means every owner is part of the loan.

This guide explains who has to sign, what they’re agreeing to, and how to handle the practical and personal side so it doesn’t become the thing that holds the loan up.

How does co-ownership show up on the title?

Your title search shows every registered owner and, usually, how they hold the property. The two common forms:

Form of ownership	What it means	What it means for a loan
Joint tenants	Owners hold the whole property together; if one dies, the survivor generally takes the whole	Every owner signs the mortgage
Tenants in common	Each owner holds a distinct share (equal or unequal), which passes under their will	Every owner signs the mortgage over the whole property

Either way, lenders almost always require a mortgage over the whole property. A mortgage over one tenant in common’s share alone is rarely acceptable security for business lending, because a lender can’t easily sell a fractional share.

If you’re not sure how your property is held, a title search will tell you. See our guide on ordering a title search.

Who signs what?

On a typical business second mortgage over a co-owned home:

• The borrower (you, or your company) signs the loan agreement.
• Every registered owner signs the mortgage.
• Owners who aren’t borrowers usually sign a guarantee, making them personally liable if the borrower doesn’t repay.
• Directors of a borrowing company usually guarantee too.

The mortgage is prepared on the National Mortgage Form, which has addendums for each state and territory covering signing and witnessing. In practice, the lender’s lawyers tell each signatory exactly how to sign and verify their identity.

What is a non-borrowing owner actually agreeing to?

This is the part worth explaining carefully at home. By signing the mortgage and a guarantee, a co-owner who isn’t in the business is agreeing that:

• the property can be used as security for a business debt they don’t control;
• if the loan isn’t repaid, the lender can pursue the guarantee and ultimately enforce the mortgage;
• the arrangement stays in place until the loan is repaid and the mortgage discharged.

For this reason, many lenders encourage or require non-borrowing owners to get independent legal advice, and some ask for a certificate confirming it. That isn’t a hurdle designed to slow things down. It protects the co-owner, the borrower and the lender by making sure everyone understands the commitment.

Worth discussing with a specialist before you raise it at home? Start an enquiry and ask how the signing would work for your title.

How do you have the conversation?

The loan documents shouldn’t be the first time a co-owner hears the detail. The files that move smoothly are the ones where the conversation happened early and covered:

1. What the money is for and why property security is being used.
2. How much is being borrowed, and how much equity stays untouched. Our equity and LVR calculator shows the buffer clearly.
3. How it will be repaid, and what happens if the plan is late. See second mortgage exit plans.
4. What they’ll sign and that they’ll get independent advice.
5. What happens next: timing, who will contact them, how signing works.

If a co-owner isn’t comfortable, it’s better to know on day one. Alternatives may exist, such as using a different property, a smaller amount or an unsecured facility.

What are the tricky co-ownership situations?

A former partner still on title. After a separation, a property settlement may have been agreed but the title never updated. The former partner is still a registered owner and would have to sign. Usually it’s better to complete the transfer first; your family lawyer or conveyancer can advise on timing.

A deceased co-owner. If the property was held as joint tenants, the survivor generally needs to register the death to update the title. If held as tenants in common, the deceased owner’s share passes through their estate. Either way, the title needs sorting before a new mortgage can be registered.

A co-owner overseas. Signing and identity verification can be done abroad, but it takes longer. Allow extra time, particularly on urgent files.

Parents or relatives. Using a family member’s property to secure your business loan is possible, but it needs their genuine, informed agreement. Independent legal advice is strongly encouraged, and lenders will want to be confident nobody is under pressure.

Mixed ownership. An individual and a trust, or a couple and a company. Each owner signs in its proper capacity. See trust or company property.

What if co-owners disagree about the loan?

It happens, and it’s better surfaced early. A co-owner may be comfortable with a smaller amount but not the full request, or happy to help with a short bridge but not a long-term loan. Those are useful signals. Adjusting the amount, shortening the term, adding a clear release point or using a different property can turn a no into a yes that everyone is comfortable with.

What doesn’t work is pressure. Lenders and lawyers are alert to signs that a guarantor or co-owner doesn’t understand the arrangement or feels they have no choice, and a file with those signs will stall, as it should. If agreement isn’t there, look at alternatives that don’t involve the shared property, such as an unsecured facility for a smaller amount or security over a property you own alone.

Can the co-owner be released later?

Sometimes. When the business loan is repaid, the mortgage is discharged and the guarantee falls away. If the plan is to refinance into a loan in the borrower’s sole name, or to move the security to another property, a co-owner can be released at that point. Agreeing that intention at the start, and building it into the exit plan, is often reassuring for a non-borrowing owner.

Does co-ownership affect how much you can borrow?

Not directly. The combined LVR is calculated on the whole property’s value and all debt secured on it, regardless of how many owners there are. What co-ownership affects is who must agree, how long signing takes, and sometimes the lender’s comfort if a non-borrowing owner has limited connection to the business.

If one co-owned property doesn’t stretch far enough, adding another property you own outright can help. See second mortgages over two properties.

How do you keep a co-owned file fast?

• Tell the lender about every owner upfront, including anyone you’d rather not involve.
• Line up identity documents for every signatory: licence or passport, current and matching the title name.
• Book independent legal advice early for non-borrowing owners, so it’s done before the documents arrive.
• Agree availability for signing, especially if anyone travels.
• Resolve title issues first: an old spouse’s name, a deceased owner, a change of name.

Our documents checklist has the full list of what every file needs.

Illustrative example: a smooth co-owned file

A couple own their home as joint tenants; one runs an electrical contracting business needing $160,000 for materials on a school project. Before enquiring, they discuss the purpose, the 18-month exit from project income, and the fact that about 40% of the home’s value will remain as a buffer. The non-borrowing partner books an appointment with a lawyer for independent advice. When the documents arrive, both sign within a day and the loan settles that week. The scenario is illustrative.

Everyone on board? Let’s check what the property supports

When every owner understands the plan, co-owned property is straightforward security. The enquiry takes about 60 seconds and there’s no credit check when you first enquire.

We don’t circulate your details among multiple lenders. One specialist reviews your situation, including who’s on title, and calls you back to explain how signing and guarantees would work. Please list every registered owner accurately on the form; getting that right at the start is the difference between a file that settles this week and one that waits for a signature.

See what our property could support →