Using Equity to Buy Another Property — How Remortgaging Funds Portfolio Growth

Equity as a Deposit Engine

The most reliable way to grow a buy-to-let portfolio without injecting large amounts of fresh savings is to recycle the equity that has built up in existing properties. As property values rise and mortgage balances reduce, the gap between a property's market value and its outstanding mortgage — its equity — can be unlocked through remortgaging and used as a deposit on the next acquisition.

This is sometimes described as "using the bank's money to make money", though it is more accurately described as leveraging unrealised capital growth into a new productive asset.

How Equity Release Works

When you remortgage a property, a new lender (or your existing lender via a product transfer with additional borrowing) lends you a larger amount than your current outstanding mortgage. The existing mortgage is repaid, and the surplus funds are paid to you as a lump sum.

**Example:**

• Current property value: £280,000
• Outstanding mortgage: £140,000 (50% LTV)
• Remortgage to 75% LTV: £210,000
• Net cash released: £70,000 (after repaying existing £140,000 mortgage)

That £70,000 can then be used as the 25% deposit on a new buy-to-let property worth up to £280,000.

What Lenders Will Allow

Buy-to-let lenders generally cap remortgage LTV at 75%, though some specialist lenders will go to 80% in select circumstances. The key affordability test is whether the rental income on the remortgaged property covers the new, higher mortgage payment at a stressed rate.

Typical rental coverage requirements in 2026:

• 125% of monthly interest at a stress rate of 5.5–6.0% (basic-rate taxpayer)
• 145% of monthly interest at the same stress rate (higher-rate taxpayer)

If your property's rent does not meet this test at 75% LTV, you may need to remortgage to a lower LTV — reducing the equity you can release.

Portfolio Landlord Assessment

Once you hold four or more mortgaged buy-to-let properties, lenders apply portfolio landlord rules. In addition to the individual property's rental stress test, the lender will review:

• Your total portfolio rental income vs total portfolio mortgage payments
• Overall portfolio LTV (most lenders want to see a portfolio-wide LTV below 75%)
• Cash reserves held (some lenders require three to six months' portfolio mortgage payments in accessible savings)

This assessment can make equity release more complex as a portfolio grows. Lenders who specialise in portfolio landlords — including several challenger banks — may offer more pragmatic underwriting than high-street lenders.

Timing the Remortgage

The optimal time to remortgage for equity release is typically:

• At the end of a fixed-rate period, to avoid early repayment charges
• After a period of capital growth in the local market
• When you have a specific acquisition in mind — equity released for an undefined future purpose has carrying costs (higher monthly payments) that erode returns if it sits idle

Risks to Manage

Releasing equity increases your total debt and monthly mortgage costs. The properties in your portfolio must generate enough rental income to remain cash-flow positive after the higher payments. Model this carefully before proceeding — our [Portfolio Yield Calculator](/portfolio-yield-calculator) allows you to input revised mortgage balances and rates to check the impact on your blended cash flow before you commit.