If you want to release equity from your property, remortgaging is the route most homeowners consider first, and for good reason: it is widely available, well understood, and typically offers the lowest rate. But it is not the only option. A HELOC provides an alternative route, adding a revolving facility alongside the existing mortgage rather than replacing it. The two options achieve the same outcome, cash released from the property, but they work differently, cost differently, and suit different circumstances.

The decision is not as simple as comparing the interest rates. The remortgage rate is almost always lower than the HELOC rate, but remortgaging means giving up the existing mortgage deal, which may have a rate the borrower cannot replicate today. This guide works through the full cost comparison with verified figures, covers the hidden costs on both sides, and sets out when each route makes more sense. All figures are illustrative only.

How each option works

A remortgage replaces the existing mortgage entirely. The borrower takes a new, larger mortgage with a new lender (or the same lender on a new deal), and the difference between the new mortgage and the old one is released as cash. For example, a borrower with a £180,000 mortgage on a £350,000 property could remortgage to £230,000 and receive £50,000. The old mortgage is paid off, the new mortgage takes its place as the first charge, and the borrower makes a single monthly payment at the new rate.

A HELOC sits alongside the existing mortgage as a second charge. The existing mortgage remains untouched: same lender, same rate, same payment. The HELOC is a separate facility with its own rate, its own fees, and its own monthly payment. The borrower makes two payments each month: one to the mortgage lender and one to the HELOC provider. The combined LTV (existing mortgage plus full HELOC facility) is typically capped at 85% of the property value.

This structural difference drives everything else. The remortgage changes the entire mortgage position: rate, term, lender, and monthly payment all change. The HELOC changes only the borrowing above the existing mortgage, leaving the rest of the position intact. Whether this distinction matters depends on how favourable the existing mortgage deal is.

The hidden cost of remortgaging: losing your existing rate

When comparing a remortgage with a HELOC, most people compare the rate on the borrowed amount. The remortgage rate (as a first charge) is almost always lower than the HELOC rate (as a second charge). On this basis alone, remortgaging looks cheaper. But this comparison ignores the impact on the existing mortgage balance.

When a borrower remortgages, the entire mortgage balance, not just the new equity release portion, moves to the new rate. If the borrower is on a favourable rate that they cannot replicate in today’s market, this creates a hidden cost. The existing balance is now being charged at a higher rate than it was before.

This hidden cost does not apply to a HELOC, because the existing mortgage stays on its existing rate. The HELOC rate is higher, but it applies only to the new borrowing, not to the entire mortgage balance. For borrowers on favourable rates they want to preserve, this distinction can be significant enough to make the HELOC the cheaper overall option despite its higher rate on the borrowed portion.

If the existing mortgage deal is ending (the rate is reverting to the lender’s standard variable rate) or the current rate is no longer competitive compared with what is available today, this hidden cost disappears. In that scenario, the borrower is replacing an uncompetitive rate with a better one, making remortgaging the clearly cheaper route.

Cost comparison: isolating the £50,000

The comparison below isolates the cost of accessing £50,000 through each route. It uses the same borrower profile and focuses on the cost of the equity release itself, before accounting for the hidden rate impact on the existing mortgage (which is covered in the section above).

Two important nuances in this comparison. First, the HELOC total term is 20 years (5-year draw plus 15-year repayment) while the remortgage term is 25 years. The HELOC borrower is debt-free on this portion five years sooner, but the repayment-period payment (£492) is significantly higher than the remortgage payment (£269). Second, the HELOC’s total interest (£59,900) is substantially higher than the remortgage total interest (£30,800) despite the shorter term, because the HELOC rate is double the remortgage rate and no capital is repaid during the five-year draw period. The guide to HELOC fees and costs covers the full fee breakdown.

When remortgaging is the better route

Remortgaging is typically the cheaper and simpler route when the existing mortgage deal is ending or is no longer competitive. If the borrower is already on the lender’s standard variable rate (SVR) or the existing fixed-rate period is about to expire, there is no favourable rate to protect and no ERCs to pay. In this situation, remortgaging replaces an uncompetitive rate with a better one and releases equity at the same time, achieving two goals with a single transaction.

Remortgaging also suits borrowers who want a single monthly payment rather than managing two separate facilities (mortgage plus HELOC). A single mortgage is simpler to administer, easier to budget for, and involves one set of terms rather than two. For borrowers who need a large lump sum on day one and do not need revolving access, remortgaging provides the funds at the lowest available rate without the complexity of a second charge.

The process is slower than a HELOC application. A full remortgage involves a new mortgage application, a property valuation, legal work to discharge the old mortgage and register the new one, and a completion timeline that can take several weeks to a few months. For borrowers who need funds quickly, this timeline may be a limiting factor. The guide to how long a secured loan takes covers the factors affecting timeline.

When a HELOC is the better route

A HELOC is typically the better route when the existing mortgage rate is favourable and worth preserving. If the borrower locked in a competitive fixed rate before rates rose, giving up that rate to remortgage can cost more in additional interest on the existing balance than the HELOC’s higher rate on the new borrowing. The hidden cost analysis above shows how this works in practice.

A HELOC also suits borrowers who need funds in stages rather than as a lump sum. A phased home improvement project, for example, involves payments spread over several months. With a HELOC, the borrower draws as invoices arrive and pays interest only on the drawn balance. With a remortgage, the full amount is released on day one and interest is charged on it immediately, even if the builder is not paid until month four. The guide to using a HELOC for home improvements covers this advantage in detail.

Speed can also be a factor. A HELOC application, particularly with a straightforward property and clean credit, can complete in days to a few weeks, which is typically faster than a full remortgage. For borrowers who need funds relatively quickly and do not want to wait for the remortgage process to complete, a HELOC provides a faster route.

The HELOC products currently available in the UK do not carry early repayment charges, which means the borrower retains full flexibility to repay, refinance, or switch to a remortgage at a later date without penalty. If the existing mortgage deal ends in a year or two, the borrower could take a HELOC now to access the equity, then remortgage when the deal expires to consolidate everything at a lower first-charge rate. This staged approach avoids paying ERCs on the current mortgage while still accessing the equity now.

Can you do both?

Yes. The two options are not mutually exclusive, and for some borrowers a combined approach captures the advantages of both. The borrower remortgages to release the bulk of the equity at the lower first-charge rate, and takes a smaller HELOC alongside the new mortgage for revolving access to a further amount.

This approach works best for larger total equity release needs where the borrower wants most of the funds as a lump sum (at the lowest rate) but also wants ongoing drawdown flexibility for a smaller portion. For example, a borrower releasing £80,000 could remortgage to access £60,000 at the first-charge rate and take a £20,000 HELOC for phased costs or contingency access.

The trade-off is two sets of fees: remortgage fees on the new mortgage and lender plus broker fees on the HELOC. This only makes financial sense if the rate saving on the remortgaged portion outweighs the additional cost of the HELOC fees. For smaller total amounts (under £30,000 to £40,000), the double-fee burden is unlikely to be cost-effective. A broker who understands both markets can model the combined cost against a single-product approach to determine which structure works best for the specific situation.

Frequently asked questions

Is a remortgage always cheaper than a HELOC?

On the borrowed amount alone, a remortgage is almost always cheaper because first-charge rates are lower than second-charge rates. A borrower releasing £50,000 will pay less interest on that amount through a remortgage at 4% to 5% than through a HELOC at 8% to 10%. The remortgage fees (typically £1,000 to £2,000 for arrangement and legal costs) are also generally lower than the combined HELOC fees (lender product fee, arrangement fee, and broker fee). On a straight comparison of the borrowed amount, the remortgage wins in almost every scenario.

However, the total cost depends on what happens to the existing mortgage balance. If the borrower is on a favourable rate, say 3% on a fix secured before rates rose, and remortgaging moves the entire balance to 4.2%, the extra interest on the existing £180,000 costs approximately £2,160 per year. Over the remaining years of the new deal, this amounts to thousands of pounds. This hidden cost narrows the gap between the two options, but under typical illustrative rates, the remortgage remains cheaper on total cost even after the hidden cost is factored in. The gap can only be closed by the hidden cost for borrowers on very favourable existing rates (below approximately 2%) who also draw gradually rather than as a lump sum.

On pure cost, remortgaging wins in the majority of scenarios. The HELOC’s case rests more on its structural advantages: preserving a favourable existing rate, avoiding ERCs, phased drawdown for staged spending, revolving access during the draw period, and no early repayment charges on exit. For borrowers who value these features, the higher total cost may be a price worth paying. For borrowers whose only priority is minimising total interest, remortgaging is the cheaper route in most circumstances. The cost comparison visual in this guide works through an illustrative example.

Can I remortgage and keep my existing rate?

Not through a traditional remortgage. Remortgaging means replacing the existing mortgage with a new one, which means the old rate is gone. The new mortgage will be on whatever rate the borrower qualifies for today, applied to the entire balance (existing plus new borrowing). There is no mechanism to remortgage only the new portion while keeping the existing portion on its original terms.

However, some lenders offer a “product transfer” where the borrower stays with the same lender and moves to a new deal without a full remortgage process. A product transfer may allow additional borrowing (a further advance) at a different rate while keeping the existing balance on its current terms. This effectively creates two tranches within the same mortgage: the original balance at the original rate, and the new borrowing at the new rate. This achieves something close to the structural advantage of a HELOC (new borrowing at a separate rate without disturbing the existing deal) but within a single first-charge mortgage.

The limitation is that not all lenders offer product transfers with further advances, and the rate on the further advance may not be competitive compared with the open market. The lender is under no obligation to offer a competitive rate on the additional borrowing because the borrower is not shopping around in the same way they would with a full remortgage. It is worth checking with the existing lender whether this option is available and at what rate before committing to either a full remortgage or a HELOC. The second charge vs further advance comparator can help assess whether this route is cost-effective compared with the alternatives.

How long does each option take?

A HELOC application can complete in days to a few weeks for straightforward cases (clean credit, standard property, readily available documentation, AVM valuation). More complex applications, including those involving adverse credit, non-standard properties, self-employed income, or a RICS valuation, may take two to four weeks. If the HELOC facility is already in place (pre-approved and available to draw), accessing the funds is immediate because the borrower simply makes a drawdown request.

A full remortgage typically takes four to eight weeks from application to completion, and can take longer if there are complications. Common causes of delay include slow responses from the existing lender (who must provide a redemption statement and consent to the new charge), property valuation issues, legal complications with the title, or a complex income assessment. If the borrower is remortgaging with the same lender via a product transfer, the process is usually faster because the lender already holds the mortgage and property information.

The speed difference matters most when the funds are needed for a time-sensitive purpose. A borrower who needs to pay a builder’s first invoice next week cannot wait six weeks for a remortgage to complete. A borrower who is planning ahead for a project starting in three months has the luxury of choosing the slower but potentially cheaper route. For borrowers who need equity now but whose mortgage deal is ending in six to twelve months, the staged approach (HELOC now, remortgage later to consolidate) captures the speed of the HELOC without permanently committing to its higher rate.

What if I have adverse credit?

Both options are affected by adverse credit, but the impact differs because the two markets are structured differently. The remortgage market is broader than the HELOC market, with more lenders competing for business including specialist providers who cater to borrowers with missed payments, defaults, and CCJs. This means there are more product options available for adverse credit borrowers through the remortgage route, though the rates offered will be higher than for clean credit borrowers.

The complication is that remortgaging with adverse credit may mean accepting a rate that is higher than the borrower’s existing deal. If the borrower is on a 3.5% fix and the best adverse credit remortgage available is 6.5%, moving the entire balance to 6.5% represents a significant increase in the monthly payment and total interest cost, not just on the new borrowing but on the existing balance too. In this scenario, a HELOC at 10% on the new borrowing alone may actually cost less in total than a remortgage at 6.5% on the entire balance, because the HELOC leaves the existing 3.5% rate untouched.

For borrowers with adverse credit, the decision between remortgaging and a HELOC often comes down to the gap between the existing mortgage rate and the best remortgage rate available given the credit profile. If adverse credit pushes the available remortgage rate above the existing rate, the HELOC becomes more attractive despite its higher rate on the borrowed portion. A specialist broker who works across both markets can model both options against the borrower’s specific credit profile and existing deal. The guide to getting a HELOC with bad credit covers the eligibility picture for adverse credit borrowers, and the guide to secured loans for bad credit covers the wider secured lending options.

Can I switch from a HELOC to a remortgage later?

Yes, and this is one of the most practical strategies for borrowers who need equity now but whose existing mortgage deal has not yet expired. The HELOC products currently available in the UK do not carry early repayment charges, so the borrower can repay the HELOC in full at any time without penalty. When the existing mortgage deal ends (and the rate reverts to the lender’s SVR or the fixed period expires), the borrower remortgages at that point, sizing the new mortgage to include the outstanding HELOC balance. This consolidates everything into a single first-charge mortgage at the lower first-charge rate.

The maths on this staged approach can work well. The borrower pays the higher HELOC rate for a limited period (the time until the mortgage deal expires), avoids paying ERCs on the current mortgage, preserves the favourable existing rate on the bulk of their borrowing, and then moves everything to a competitive first-charge rate at the point when the existing deal was going to end anyway. The total cost of the HELOC for this interim period (rate plus fees) must be compared against the cost of breaking the existing mortgage early (ERCs plus the rate increase on the full balance) to confirm that the staged approach is cheaper.

One consideration: the borrower needs to qualify for the remortgage at the point they apply, which may be one to three years in the future. If circumstances change (income drops, credit deteriorates, property value falls), the remortgage may not be available on the terms expected. The HELOC continues on its own terms regardless, so the borrower is not left without options, but the planned consolidation may not materialise as expected. Building in some flexibility around the timing of the switch, rather than relying on a specific date, is prudent. The guide to refinancing a HELOC covers the full range of transition options.

This article is for informational purposes only and does not constitute financial advice. Your home may be at risk if you do not keep up repayments on a mortgage or other debt secured against it. The cost comparisons shown are illustrative and simplified. Actual costs depend on your existing mortgage rate, the remortgage rate available, HELOC rates and fees, early repayment charges, and the term chosen. Rates, fees, and product availability change over time. Actual outcomes will depend on your individual circumstances.