Remortgaging a Buy to Let Property to Expand Your Portfolio
Remortgaging a buy to let property is one of the most common ways landlords grow from owning one investment property to building a larger portfolio. The principle is simple: release equity from an existing property to help fund the deposit on the next one. In practice, the numbers need to stack up, and lender criteria are tighter than many investors expect.
This guide explains how buy to let remortgaging works in the real world, what lenders look at, and how to approach portfolio growth sensibly.
How Buy to Let Remortgaging Works
When you remortgage an investment property, the lender reassesses it as if it were a new application. They look at:
The current property value
The outstanding mortgage balance
Rental income and stress testing
Your wider financial position
If there is sufficient equity, you may be able to borrow more than your existing mortgage balance. The additional borrowing is typically released as cash, which can then be used as a deposit for another buy to let purchase.
This process is often repeated over time. Property A helps fund Property B. Once both are established, they may jointly support the purchase of Property C, and so on.
Equity Release Is Not Guaranteed
A common misconception is that rising property values automatically mean large equity releases. In reality, lenders cap borrowing based on rental income stress tests, not just value.
Even if a property has increased significantly in value, you may not be able to extract as much equity as expected if:
Rental income no longer meets current stress test requirements
Interest rate assumptions have increased
Portfolio-level affordability is stretched
This is why landlords are often surprised by lower-than-expected release figures.
Rental Stress Tests Matter More Than Ever
For buy to let remortgages, rental income must usually exceed the mortgage payment by a set margin under a stressed interest rate.
Key points to understand:
Stress tests apply to the existing property being remortgaged
They also apply to the onward purchase
Higher rates reduce how much you can borrow, even if rent is strong
If either property fails the stress test, it can limit or block portfolio expansion entirely.
Deposits for the Next Purchase
When using released equity to buy another investment property, most lenders still expect a deposit of around 25% or more of the new property’s value.
Equity release usually covers part or all of this deposit, but you should also plan for:
Stamp duty and additional property surcharge
Legal fees
Valuation and broker costs
Potential refurbishment or contingency funds
Cash flow planning is just as important as securing the mortgage itself.
Portfolio Landlord Assessments
Once you own multiple buy to let properties, lenders no longer look at each application in isolation. Instead, they assess your entire portfolio.
This can include:
A schedule of all properties owned
Outstanding mortgage balances
Rental income across the portfolio
Overall profitability and leverage
Stricter background checks are common at this stage, and weak properties can affect borrowing on stronger ones.
A Practical Step-by-Step Approach
A sensible remortgage-led growth strategy usually follows these steps:
Obtain an up-to-date valuation on the existing property
Review current rental income against today’s stress tests
Calculate realistic equity release figures
Assess deposit requirements for the next purchase
Model cash flow for both properties together
This avoids overcommitting and reduces the risk of stalled applications.
Why Advice Matters for Portfolio Growth
Remortgaging to grow a rental portfolio is not about chasing the maximum loan available. It is about building something sustainable.
We focus on:
Accurate equity calculations, not optimistic assumptions
Checking rental viability before any application is submitted
Mapping portfolio growth step by step, not all at once
There are no guaranteed equity release amounts, and no promises that every portfolio can be expanded indefinitely. The numbers must work under current lending rules.
The Bottom Line
Remortgaging a buy to let property can be an effective way to grow a rental portfolio, and it is how many landlords scale from one property to several. However, success depends on rental income, stress tests, deposit planning, and how your full portfolio is assessed.
With clear figures and a structured plan, it is possible to expand steadily without taking on unnecessary risk.
