Regulated Buy-to-Let Mortgages Explained: A Landlord's Guide for Family Tenants

Regulated buy-to-let mortgages explained (family BTL)

If you want to buy a property to rent to a relative, you may need a regulated buy-to-let mortgage—often referred to as a family buy-to-let. This is a specialist type of lending designed for situations where a family member will occupy a significant part of the home.

In this guide, we’ll explain what regulated buy-to-let means, how it differs from standard buy-to-let, and what to consider before you apply.

When does a buy-to-let become “regulated”?

A key factor is how much of the property your relative occupies.

• If the relative occupies 40% or less of the property, you may be able to use a standard (unregulated) buy-to-let.
• If the relative occupies more than 40%, you may need a regulated buy-to-let mortgage.

This “40% rule” is why many family arrangements fall into the regulated category—because the relative is often living in the property alongside other tenants, or the property is effectively being used as a family home with rental income from tenants.

Note: exact treatment can depend on the lender’s interpretation of the occupancy and the specific facts of the case.

What is a regulated buy-to-let mortgage?

A regulated buy-to-let mortgage is a mortgage where the lending is regulated by the FCA (Financial Conduct Authority). It’s designed for cases where you’re renting the property to a relative who occupies more than 40%.

Compared with standard buy-to-let, regulated products typically involve more borrower-focused underwriting and may require more evidence about affordability and the overall arrangement.

Why lenders treat family buy-to-let as higher risk

Lenders may view family arrangements differently from typical tenancies. For example:

• rent may be lower than market rates
• family members may be more likely to allow missed payments to continue for longer

Because of this, lenders often require robust information to show the mortgage can be serviced.

Regulated vs unregulated buy-to-let: what’s the difference?

Here’s a practical way to think about it:

The exact approach varies by lender, but the overall theme is consistent: regulated family BTL is more about affordability and risk controls, not just projected rent.

Common family buy-to-let scenarios

A regulated buy-to-let mortgage may be relevant if, for example:

• you’re buying for a child to live in, while also renting out part of the property
• you want a parent or grandparent to move into the property you’re purchasing
• you plan to live in the property yourself alongside a tenant
• a sibling (and possibly their household) will occupy a large share of the property while other tenants pay rent

Which family members are usually considered?

Lenders typically expect the arrangement to involve close family. While exact definitions can vary, regulated family buy-to-let is commonly aimed at relationships such as:

• child
• sibling
• parent
• grandparent

More distant relatives (for example, cousins or aunts/uncles) are often less likely to fit lender expectations for this niche product.

What lenders look at in a regulated family BTL application

Because regulated buy-to-let is treated more like a residential mortgage in terms of regulation, the application is usually assessed with affordability at the centre.

That means lenders may consider things such as:

• your income and outgoings
• existing financial commitments
• the mortgage structure you’re applying for (for example, repayment vs interest-only)
• the overall risk of the arrangement

In practice, this is why a regulated family BTL can feel more complex than a straightforward buy-to-let application.

How a buy-to-let broker can help

Regulated family buy-to-let is a niche area. A specialist broker can help you:

• confirm whether your plan is likely to be treated as regulated or unregulated
• prepare the application in a way that matches how lenders assess these cases
• identify lenders that may consider family occupancy arrangements
• avoid wasting time with the wrong product type

Providers (examples)

The lender pool for regulated family buy-to-let is typically smaller than for standard buy-to-let. Some lenders that have been known to consider these applications include:

• Virgin Money
• Together
• Saffron for Intermediaries
• Bluestone Mortgages
• Vernon Building Society

Availability and lending policies can change, so it’s important to review your options with a broker who can check current criteria.

Tip: don’t rely on a list of “known” lenders—your eligibility will depend on the specific facts of the case and the lender’s current policy.

What happens if you choose the wrong type of mortgage?

If you apply for an unregulated buy-to-let when the arrangement actually requires regulated treatment (for example, because a relative occupies more than 40%), you may create problems later.

For instance, if the occupancy situation doesn’t match what was agreed, the lender may seek remedies under the mortgage contract. In the worst case, this could lead to the mortgage needing to be repaid.

If you’re unsure, it’s worth getting clarity before you apply.

Can you switch later?

If your circumstances change—such as you (or your family) moving into the property more permanently—you may be able to remortgage onto a regulated option.

Whether that’s possible depends on your lender, your equity, and your affordability at the time. A broker can help you plan the next step and compare options.

Speak to a broker for regulated family buy-to-let

A regulated buy-to-let mortgage can be the right solution for family arrangements, but it’s not a one-size-fits-all product. With the right guidance, you can make sure your application reflects the true occupancy and risk profile lenders expect.

If you’d like to discuss your situation, speak to a specialist buy-to-let broker who can help you map out the most suitable route.