Home Loan Portability: Transferring Your Loan When Buying and Selling

RBA data confirms that the average owner-occupier variable rate for new loans settled in June 2024 was 6.27% p.a., while many borrowers still hold loans priced at 2.50%–3.50% p.a. from the pre‑2022 era. When these homeowners attempt to upsize, downsize, or relocate, a standard refinance forces them through a fresh credit assessment under today’s 9.00%‑plus serviceability floor. APRA’s 6 October 2021 instruction to raise the mortgage serviceability buffer from 2.5 to 3.5 percentage points, combined with the RBA’s thirteen cash‑rate increases that took the cash rate from 0.10% to 4.35% between May 2022 and November 2023, has erected a wall that catches perfectly creditworthy households. The result is a growing pool of “mortgage prisoners”: borrowers who can comfortably service their existing debt but cannot qualify for a new loan of the same size. Home loan portability—substituting one security property for another while retaining the original loan contract—has therefore shifted from a niche convenience to a strategic tool. Lenders’ portability policies, however, are far from uniform. Assessment triggers, LVR caps, DTI limits, and the treatment of construction or bridging components differ materially between the major banks and non‑bank lenders. Getting it wrong means an unexpected credit hit, a forced rate reset, or a deal that collapses six weeks into settlement.

What Loan Portability Actually Is—and What It Is Not

A portable loan is not a new loan. It is an amendment to the existing facility that allows the borrower to replace the current security property with a new one while preserving the original loan balance, contractual interest rate, remaining term, and repayment type. The distinction matters because it circumvents the full serviceability assessment that a refinance or new application would trigger.

The Substitution of Security Mechanism

Legally, portability is achieved through a substitution of security. The lender releases the mortgage over property A and simultaneously takes a new mortgage over property B. The loan account, its number, its rate, and its linked offset account often remain unchanged. The borrower pays a portability fee—typically $300–$600 at a major bank—plus government charges for the discharge and registration of the new mortgage. Because the credit contract is not novated, the lender is not required to reassess the borrower under the current prudential standard APS 220 in the same way it would for a new approval, unless certain triggers are met.

How Credit Assessment Differs from a Refinance

A full refinance forces the applicant through the 3.5‑percentage‑point APRA buffer (or the lender’s own floor rate, whichever is higher) and a complete living‑expense verification. Portability, by contrast, typically triggers a truncated assessment that focuses on the “delta” between the old and new arrangements. If the loan amount, loan term, and borrower structure remain identical, Westpac’s credit policy (version 23.1, effective 1 March 2024) states that no new income verification is required, provided the existing loan has not fallen into arrears of more than 30 days in the past 12 months. NAB’s “Same Security Substitution” framework goes further: where the loan is not increased and the security value is sufficient, NAB waives the serviceability buffer calculation entirely, bypassing the 9.00%‑plus floor rate hurdle that would apply to a new application.

But the moment a borrower requests a top‑up, a term extension, or a change from principal‑and‑interest to interest‑only, the portability shield breaks. The lender then runs a full serviceability test, often at the current assessment rate. The buffer math is unforgiving. For a borrower earning $180,000 p.a. gross with no other debt, a $600,000 P&I loan at 2.99% p.a. costs $2,524 per month. Under a 9.00% assessment rate, the calculated repayment jumps to $4,834, and the serviceability margin shrinks drastically. Many borrowers who could comfortably carry the actual repayment fail the test.

Why Portability Has Become the Pivot in 2024–25

The value of portability is directly proportional to the gap between a borrower’s existing rate and the prevailing new‑customer rate, and inversely proportional to the ease of requalifying. Both forces are aligned right now.

The 3.5‑Percentage‑Point Buffer Trap

APRA’s directive of 6 October 2021 moved the serviceability buffer from 2.5% to 3.5%. When the cash rate was 0.10%, the effective assessment floor was around 5.00–5.50%. By late 2023, with the cash rate at 4.35% and standard variable rates at 6.50–7.00%, the assessment rate hit 10.00% or higher for many lenders. Although APRA confirmed on 22 July 2024 that it would retain the buffer at 3.5% for now, the sheer level of today’s floor rate has locked out tens of thousands of households. Portability allows these households to sidestep the buffer, provided they do not alter the facility.

Data from the Australian Bureau of Statistics’ Lending Indicators release (June 2024, published 2 August 2024) shows external refinancing volumes fell 32% from the May 2022 peak, while property transaction volumes—driven by upsizers and downsizers—remained relatively stable. This divergence underscores the role portability is playing: borrowers are selling and buying but staying with their existing lender.

Falling Property Values and LVR Constraints

Portability also helps when the new property is worth less than the old one. If a borrower is moving from a $1.2 million house to a $900,000 apartment, a new loan would require an LVR reassessment and potentially LMI if the ratio exceeds 80%. With portability, as long as the new security value covers the outstanding loan balance and the LVR remains within the lender’s original policy limit (say 80% or 90% dependent on the product), the deal proceeds without LMI reappraisal. CBA’s “Security Swap” policy explicitly permits porting when the new LVR is up to 95% inclusive of capitalised LMI, provided the original loan already had LMI and the borrower does not increase the loan amount. This is critical in markets where median dwelling values have slipped 5–10% from their 2022 peaks, increasing the probability that an existing borrower’s equity cushion has thinned.

Lender‑by‑Lender: Who Permits What

The surface‑level promise of “just swap the property” masks a complex matrix of lender‑specific rules. Product type, LVR thresholds, DTI ceilings, and the treatment of bridging periods all vary substantially.

Big‑Four Bank Portability Rules

• CBA: Allows substitution of security for both owner‑occupied and investment loans. No income reassessment if the loan amount does not increase, the loan purpose remains unchanged, and the new security is an acceptable residential property. If the new property is under construction, CBA treats the transaction as a construction loan variation and will reassess. Maximum LVR for portability without new LMI is 90% (or 95% if existing LMI is carried forward). Portability fee: $300.
• Westpac: Permits “Switch of Security” with a flat $350 fee. If the new loan amount is within $50,000 of the original, Westpac does not run a full serviceability test, but will verify employment status. DTI must not exceed 7× after the switch, measured against the original loan balance. Construction security switches are treated as new applications.
• NAB: Offers one of the most flexible frameworks. “Same Security Substitution” waives income verification and the buffer if the loan amount, term, and product features are unchanged. NAB will port across property types—house to unit, for example—but will not port from a standard residential security to a rural or commercial security without reassessment.
• ANZ: Allows “Security Substitution” with a $300 fee. Income reassessment is triggered if the borrower requests any change to the loan structure, including a new offset account or a change in repayment frequency. ANZ’s policy documents note that any top‑up, even $1, will trigger a full credit review.

Non‑Bank Lender Flexibility

Non‑banks often write loans that the majors decline, so their portability policies become important for borrowers who originally used a non‑bank due to credit impairment or complex income.

• Resimac: Permits substitution of security on its full‑doc and alt‑doc products. No reassessment if loan amount and borrower structure are unchanged. Resimac applies its standard LVR caps—80% for full‑doc, 70% for alt‑doc—to the new security. If the new property’s value pushes LVR above the cap, the borrower must pay down the difference. Portability fee: $495.
• Pepper Money: Will consider portability on a case‑by‑case basis. Where the original loan was underwritten with a specialist credit assessment, Pepper typically requires a full serviceability test, effectively nullifying the rate‑preservation benefit. Brokers report that portability approval rates at Pepper are lower than at the majors, constrained by the higher DTI limits (9×) that Pepper applies.
• Liberty Financial: Offers “Security Swap” only for its custom and prime products. Liberty charges a $750 fee and requires a desktop valuation. If the LVR exceeds 70%, Liberty may require a full valuation and can request a principal reduction. Liberty does not permit security swaps on construction loans.

The Bridging and Construction Overlap

Many portability scenarios involve a timing mismatch: the sale of the old property settles after the purchase of the new one. Portability in its pure form assumes simultaneous settlement, which rarely occurs. To bridge the gap, lenders often require a bridging loan that sits alongside the portable facility. Westpac’s “Switch of Security with Bridging” product allows the borrower to port the existing loan to the new property and simultaneously establish a bridging facility for the residual funds needed. The bridging portion is assessed at the new‑lending buffer, exposing the borrower to the 3.5% floor on that component. CBA, NAB, and ANZ offer similar structures, but all treat the bridging portion as a new credit application. The effective outcome is partial portability: the original loan rate and terms are preserved on the core debt, while the bridging debt attracts today’s higher rates and a full serviceability filter.

Construction loans introduce another complication. An existing residential mortgage ported to a property that is off‑the‑plan or under construction will almost invariably trigger a construction‑loan reassessment. Lenders reason that the risk profile changes because the security is not immediately habitable and progress drawdowns alter the outstanding balance dynamic. CBA’s policy explicitly states that any substitution of security involving a construction component will be treated as a new home loan application, with full income, expense, and buffer verification.

When the Portability Shield Cracks

Borrowers often discover too late that what they assumed was a straightforward port is deemed a new facility by the lender. Three common triggers unwind the portability pathway.

Top‑Up and Split Loan Requests

A borrower selling a $1.0 million home with a $400,000 loan who buys a $1.4 million property may need an additional $200,000. The temptation is to “port and top‑up”—keep the existing $400,000 and borrow a new $200,000 tranche. Lenders will allow this, but the top‑up component is always assessed as a new application. Worse, some lenders aggregate total debt for serviceability when a top‑up occurs alongside a port. ANZ’s credit manual states that if a top‑up and substitution of security are applied simultaneously, the entire aggregate debt must be serviceable at the current assessment rate, effectively stripping the ported portion of its protected status. Brokers circumvent this by sequencing: port the existing loan first, then apply for a separate top‑up facility after settlement. However, lenders are increasingly wise to the practise and have introduced clauses that treat any top‑up within 90 days of a port as part of the same transaction.

Changes in Borrower Structure

Portability is built on the premise that the covenant remains identical. If a borrower going through a separation wants to port the loan solely into their name, or add a new partner to the title, the lender sees a new borrower entity. That triggers a fresh application under NCCP responsible‑lending obligations. Even a simple change from joint tenants to tenants‑in‑common can prompt a reassessment. The buffer maths applies in full. A borrower who could pass serviceability at 7.00% actual rate may fail at 10.00%, collapsing the deal.

Property Type Switches

Moving from a freestanding house in a capital city to an apartment in a high‑density postcode or a rural property changes the security risk profile. Lenders have exposure caps by postcode and property type. ANZ, for example, restricts maximum LVR to 80% for apartments in certain inner‑city postcodes, whereas the original house loan may have been written at 90% LVR. Porting to a property that falls outside the lender’s acceptable security policy results in a decline, regardless of borrower strength. Non‑banks are sometimes more flexible on location but stricter on LVR. Pepper Money’s standard policy caps any security substitution at 70% LVR for postcodes with a SEIFA index below 5.

Five Specific Steps to Execute a Portable Loan Without Losing the Rate Advantage

1. Demand a written pre‑approval for the substitution of security before making an offer on a property. A generic “portability is available” statement in a product fact sheet is not a binding commitment. Submit the specific address, valuation estimate, and a clear statement that no loan increase is sought. Most lenders will issue a security‑approval letter that states conditions.

2. Isolate any top‑up or bridging component into a separate facility and complete the pure port first. Where possible, delay the additional borrowing by at least 90 days to avoid lender‑forced aggregation of debt for serviceability. Verify the aggregation clause of the lender’s credit guide, as wording differs.

3. Avoid any change to the borrower entity or loan title, even if you later intend to update it. Port the loan with the identical parties, then seek a separate title change afterward. Recognise that the title change may trigger a reassessment, but at least the rate and loan terms will already be secured on the new property.

4. Refresh your valuation data before committing. If the new property’s value has declined in a cooling market, a desktop valuation from the lender may push the LVR above the allowable cap. Obtain an independent valuation (cost approx. $400–$600) and run the numbers against the lender’s published substitution LVR limits for that postcode and dwelling type. If the LVR exceeds the cap, be prepared to contribute cash to reduce the principal.

5. Engage a mortgage broker or a credit adviser who has access to all major and non‑bank credit policies and who has executed portability transactions in the past twelve months. Lenders’ back‑end processing teams routinely misunderstand substitution rules. A broker who can escalate to a state credit manager and cite the exact policy clause (e.g., NAB’s “Same Security Substitution” version 14.2 effective 12 February 2024) will cut weeks off the timeline and prevent a deal from being wrongly routed to a new‑lending assessment queue. The cost of a broker is almost always offset by the avoided interest‑rate reset—preserving a 2.99% rate versus taking a 6.30% rate on a $500,000 balance saves over $16,500 in interest in the first year alone.