The Reserve Bank of Australia has held the cash rate at 4.35 per cent since November 2023, and with three of the big four banks now expecting the first cut no earlier than February 2025, the home-loan landscape remains defined by high serviceability buffers and elevated monthly repayments. For an owner-occupier who bought during the pandemic fixed-rate boom, the math is stark: a $500,000 loan fixed at 1.99 per cent p.a. that rolls off onto a variable rate of 6.44 per cent p.a. adds roughly $1,170 to a monthly repayment, assuming a 25-year remaining term. In that environment, the last thing a borrower wants is to incur a break cost, discharge fee, or fresh lenders mortgage insurance premium simply because they need to move house. That is precisely where loan portability — the ability to transfer an existing home loan from the security property to a new one — becomes a financial tool worth serious scrutiny. The major banks each offer portability, but conditions vary sharply across loan purpose, interest rate type, and the borrower’s ability to meet current credit policy. National Australia Bank’s portability process sits inside a broader suite of features attached to its variable and fixed-rate products, and while it can bypass a formal refinance, it is not a blanket pass-through. The bank still re-assesses serviceability under the Australian Prudential Regulation Authority’s 3-percentage-point buffer, which APRA confirmed remains appropriate in its 28 February 2024 letter to all authorised deposit-taking institutions. That means a borrower earning $120,000 with no dependants and a $600,000 loan — comfortably serviced at the note rate — can quickly hit a wall if the buffer calculation pushes assessed repayments beyond the debt-to-income limit. With national housing turnover finally lifting after a two-year trough, more owner-occupiers are confronting the portability question, and NAB’s specific process reveals where a move can be seamless and where it can collapse at the last credit hurdle.
How NAB Defines Loan Portability
NAB classifies loan portability as the substitution of one security property for another within an existing home-loan contract, leaving the loan term, product features, and loan account number unchanged. This is distinct from a new loan application: the bank does not close the original facility and open a replacement, which is why it can preserve a legacy interest rate, an offset arrangement, or a package fee structure that would otherwise be lost in a refinance. The contractual basis is a variation to the mortgage memorandum, and the borrower must sign a new letter of offer that ties the existing loan to the replacement property. While NAB’s product disclosure documentation does not guarantee portability, it frames it as a feature available at the bank’s discretion on eligible products.
Eligible NAB Loan Products
Variable-rate owner-occupier principal-and-interest loans make up the core of portability requests and are generally supported. NAB’s Tailored Home Loan, Base Variable Rate Home Loan, and the Choice Package all permit portability, subject to credit assessment, provided the borrower meets the product’s ongoing lending criteria at the time of the move. Fixed-rate loans can be portable, but the bank’s position has tightened since the rapid rate rises of 2022-23. When a fixed-rate loan is ported, NAB typically requires the rate to be re-priced to the current fixed offering unless the move occurs within a narrow window — usually the first 12 months of the fixed term — and even then, break-cost economics can nullify the benefit. NAB’s fixed-rate portability guide, last updated 15 March 2024, states that any increase in loan amount or change to loan purpose (for example, moving from owner-occupier to investment) will trigger a full reprice. Borrowers who split their loan across fixed and variable tranches can often port the variable component intact while the fixed portion is unwound at cost.
Ineligible Facilities and Exclusions
Guarantor-backed Family Pledge loans, Defence Force Home Loans, and Portfolio Facility lines are excluded from standard portability. Construction loans halfway through a progress-payment schedule cannot be ported directly; the borrower must either complete the build and convert the loan to a standard variable facility, or discharge and apply for a new construction product. Interest-only periods add a further layer: an interest-only loan can be ported, but the remaining interest-only term does not reset automatically, and if the borrower has already used three years of a five-year interest-only window, only the residual two years transfer across. That timeline matters acutely when the replacement property will be tenanted during a transition, as the ATO’s six-year rule for main residence exemption does not interact with the loan’s contractual interest-only term, but it can influence the lending decision if the bank reclassifies the loan purpose.
NAB’s Portability Credit Assessment in Detail
Portability at NAB is not a deed substitution without credit enquiry. The bank applies a full serviceability test under the prevailing APRA prudential standard, which has remained at a 3-percentage-point interest rate buffer on top of the product’s actual rate since 21 October 2021. That means a borrower on a 6.24 per cent p.a. variable rate is assessed at 9.24 per cent p.a., and HEM-based living expenses, existing liabilities, and rental outgoings all feed into the net income surplus calculation. NAB’s own debt-to-income limit of 7.5 times for owner-occupier lending applies simultaneously, and a portability application that pushes DTI above that ceiling — even if serviceability passes — is declined unless the borrower qualifies for an exception under the bank’s professional or high-income carve-outs.
Income and Employment Verification
The borrower must supply two recent payslips, the most recent notice of assessment from the Australian Taxation Office, and a payroll or employer letter not older than 30 days. Self-employed applicants need the last two years of full financials, including profit-and-loss statements and business tax returns, compiled by a registered tax agent. NAB does not accept a letter from an accountant as a substitute for lodged returns under portability assessment; this matches its standard origination policy update of 1 July 2023. For borrowers who have changed jobs within the last six months, the bank generally requires confirmation of probation completion, unless the role is within the same industry and remuneration is on the same or higher base. Commission and bonus income is shaded to 80 per cent of the two-year average, consistent with the approach used across major banks.
Valuation and LVR Constraints
A new valuation is ordered on the replacement property, and the existing property’s value plays a role only when the borrower needs to draw additional equity to fund the shortfall between the sale and purchase prices. If the loan amount remains identical or reduces, NAB relies solely on the valuation of the incoming security. For an owner-occupied replacement property, the maximum LVR at portability is 80 per cent without LMI; above that, Genworth or QBE must be approached for a portability endorsement, and they will not automatically approve a transfer if the original LMI policy had a different risk geography or property type. The practical upshot is that a borrower who bought an inner-city Melbourne apartment at 85 per cent LVR in 2020 and is now moving to a regional Victorian house may face a fresh LMI premium, even if the loan quantum is unchanged, because the LMI provider re-underwrites the risk.
Property Type and Location Filters
NAB applies a postcode-based minimum security value threshold and a restricted-list overlay for certain high-density or remote postcodes. Apartments below 50 square metres of internal living area, serviced apartments, and properties with more than two hectares of land are excluded from standard security acceptance unless pre-approved by the bank’s credit risk team. This filter is identical to the one applied at origination, and it catches borrowers who originally financed a house on a 650-square-metre block and are now downsizing to a small inner-city unit. Commercial-zoned residential properties may be accepted at a reduced LVR of 60 per cent, but portability into a commercial-security-eligible asset that was not part of the original loan’s allowable security classes triggers a product reclassification and effectively terminates the portability pathway.
The Step-by-Step Portability Settlement Timeline
A NAB portability transaction runs on a simultaneous or near-simultaneous settlement structure. The bank will not release the old property’s title until the new property’s settlement is funded, and this creates a bridging requirement if the sale of the existing home settles after the purchase of the new one. NAB offers a Bridging Loan product to cover the gap, but it is a separate application and is assessed on the same serviceability grounds. For a genuine simultaneous settlement — where both legs occur on the same day — the portability variation is executed as a single instruction to PEXA, the electronic conveyancing platform, without a bridging component. The timeline below assumes a clean simultaneous settlement.
Pre-Application Documentation
At least 45 days before the expected settlement date, the borrower should submit a completed portability request form, a contract of sale for the existing property (unconditional), a contract of purchase for the replacement property, and evidence of deposit paid. NAB’s turnaround on portability approval is 10 to 15 business days for straightforward applications, but seasonal peak in November and March can extend this to 20 business days. The bank charges a portability variation fee of $350, which is debited from the loan account at settlement, plus a title registration fee for the new mortgage that varies by state — $147 in Victoria, $154 in New South Wales, $196 in Queensland as at 1 July 2024. These state-government charges are out-of-pocket and cannot be capitalised.
Formal Approval and Offer Document
Once credit assessment is complete, NAB issues a Variation Letter rather than a new loan offer document. This letter confirms the security substitution, any change to the loan amount (if the borrower is reducing debt with sale proceeds or increasing it to fund an upgrade), and the effective date of the variation. The borrower must sign and return it electronically within 14 days. For fixed-rate loans, the letter will state the break-cost estimate if the fixed term is being disrupted; NAB calculates break costs as the present value of the remaining interest payments compared with the current wholesale swap rate, and the figure can be substantial — a three-year fixed loan at 2.29 per cent p.a. broken in mid-2024, with two years remaining, could produce a break cost exceeding $8,000 on a $400,000 balance.
Settlement Day Mechanics
On settlement day, the bank’s settlement agent — typically an external law firm or conveyancing panel firm — attends to the PEXA workspace. The old property’s discharge of mortgage is lodged simultaneously with the new property’s incoming mortgage. Sale proceeds flow through the trust account: the outstanding loan balance is deducted, and any surplus is transferred to the borrower’s nominated offset or transaction account. If the purchase price exceeds the sale proceeds, the shortfall is funded either by increasing the loan amount (subject to approval) or by the borrower contributing fresh cash, which must be evidenced as genuine savings held in a NAB account for at least 90 days unless the source is the sale of another asset.
Costs, Risks, and When Portability Fails
Portability can save the multiple thousands of dollars that a full discharge and refinance would incur — an exit fee of $350, a new application fee of around $600 at a major bank, and potential LMI premiums on a high-LVR loan — but it is not cost-free. Beyond the $350 variation fee and state-title charges, the borrower may face a rate differential if the existing rate is below current market levels and the bank forces a reprice. That reprice is most painful on fixed-rate loans, where the break cost can wipe out the savings from avoiding a refinance. In the current rate cycle, a borrower rolling off a 1.99 per cent fixed rate in 2024 should be calculating whether portability or discharge-and-refinance yields the lower total cost over a three-year horizon, factoring in any cashback offers that may still be available from competing lenders.
Credit Assessment Failure
The most common reason a portability application fails is a serviceability shortfall. Households that were assessed at a floor rate of 5.50 per cent in 2020 and are now assessed at 9.24 per cent frequently find their borrowing capacity has shrunk by 20 to 30 per cent even without a change in income. If the replacement property requires a higher loan quantum, the numbers rarely stack. NAB will not offer a partial port; it is an all-or-nothing security substitution. The applicant must either reduce the loan amount by contributing more cash, or pursue an alternative. Brokers report that in 2023, roughly one in five portability requests at NAB were declined at credit, a figure consistent with the broader major-bank experience as the tail of low-rate originations hits the serviceability buffer.
LMI and Equity Trap
For loans originated with an LVR above 80 per cent, the LMI provider’s consent is required. Genworth has historically approved portability where the replacement property is of a similar profile — same capital city, same dwelling type, same LVR or lower. If the new property is in a regional location, a different state, or a higher-density postcode, Genworth often imposes a top-up premium or declines the transfer, forcing the borrower to either pay down the loan to 80 per cent LVR or accept a fresh LMI policy at a higher cost. A 2022 purchase in Brisbane at 88 per cent LVR ported to a Sydney property at the same loan amount can carry an additional LMI premium of $4,600, according to a Genworth premium schedule effective 1 September 2023, which the borrower must fund out of pocket.
Timing Mismatch and Bridging Costs
When the sale and purchase settlements cannot be aligned, the borrower enters NAB’s bridging ecosystem. NAB’s Bridging Loan charges a rate 1.00 to 1.25 per cent above the standard variable rate and is structured as a 12-month interest-only facility with no mandatory principal reduction during the term. The bank calculates the peak debt — the sum of the existing loan balance plus the new purchase price, less the eventual sale proceeds — and applies the serviceability test to that peak debt. Many borrowers are surprised to learn that even a short three-month bridging period can produce a substantial interest accrual: a $900,000 peak debt at 7.69 per cent p.a. for three months generates approximately $17,300 in interest, none of which is tax-deductible if the property being sold was the main residence.
Regulatory and Policy Change Risk
Portability remains a policy feature, not a regulatory requirement, and NAB reserves the right to withdraw or amend it. The Australian Securities and Investments Commission’s Report 772 on home lending, published 17 October 2023, flagged that banks’ discretionary treatment of features such as portability creates an uneven risk for consumers, particularly where the feature was marketed at origination. While ASIC stopped short of mandating minimum standards, the report has prompted some lenders to codify portability into their product terms. NAB has not yet done so, and the bank’s terms and conditions, last updated 1 March 2024, explicitly state that portability is “subject to approval and may not be available at the time of your request.” Borrowers relying on portability as a guaranteed exit strategy should therefore maintain a parallel refinance option.
How Portability Compares With a Full Refinance
A direct comparison between portability and a refinance requires isolating the net cash outflow under each path over a defined period, typically three years. Consider a borrower with a $650,000 variable-rate owner-occupier loan at 6.14 per cent p.a., moving to a property of equal value and requiring no additional borrowing. Under portability, the costs are: variation fee $350, state title-charge $154 (NSW), no LMI or break cost, total $504. Under a refinance to a comparable major-bank product at 6.04 per cent p.a. with an upfront cashback of $2,000: discharge fee $350, application fee waived, valuation and settlement fee $300, title charge $154, net cash-in of $1,196. However, the portability borrower retains the existing offset architecture and redraw balances without disruption, which can be worth more than the cash arbitrage for an owner-occupier with carefully structured finances. For a borrower with a fixed-rate loan, the refinery calculus flips sharply: break costs dominate, and portability is rarely economic unless the fixed term is nearing expiry and the bank does not force a reprice.
When Refinancing Makes More Sense
Refinancing becomes the superior option when the borrower can obtain a materially lower interest rate — a difference of 20 basis points or more over a $500,000 loan generates roughly $1,000 in annual interest savings — or when the replacement property requires a larger loan and the borrower is willing to reapply for credit. The non-bank sector, including lenders such as Athena and Tiimely, does not offer portability as a core feature, so a move from a big-four product to a non-bank will always involve a discharge. Even so, the growth in non-bank market share to 12.4 per cent of new lending flows in the March quarter 2024, as reported by the Australian Bureau of Statistics on 13 May 2024, suggests that a growing cohort of borrowers sees a full refinance as a permanent shift away from the legacy major-bank suite.
Actionable Steps for a NAB Borrower Considering Portability
A portability exercise succeeds only when the borrower treats it as a structured financial decision, not a convenient feature to be activated at the last minute. The following steps are drawn from NAB’s current policy, APRA serviceability guidelines, and documented settlement flows.
- Obtain a formal serviceability assessment from NAB at least 60 days before the planned settlement. Use the bank’s online borrowing calculator with the buffer rate of 9.24 per cent p.a. and include all existing debts, HEM living expenses, and the new loan repayment. If the surplus falls below zero or DTI moves above 7.5, a credit coach should be consulted before contracts are signed.
- Order a valuation on the replacement property early, even if this means paying for a desktop or kerbside report out of pocket before the formal application. If the valuation comes in below the purchase price, the resulting LVR gap must be filled with cash, and this must be documented as genuine savings.
- If the existing loan is fixed, request a break-cost quote from NAB’s fixed-rate team and compare it with the total cost of a full refinance, including any cashback. The quote is valid for five business days and must be refreshed if settlement is delayed.
- Coordinate the sale and purchase contracts to achieve simultaneous settlement via PEXA. A settlement gap of even one day will push the transaction into bridging territory, adding interest and requiring a separate credit assessment. Use a conveyancer experienced in simultaneous settlements and confirm with NAB’s settlement team that both legs are in the same PEXA workspace well before the date.
- Keep a parallel refinance application live with a competing lender until NAB issues the unconditional variation letter. This provides a fallback if the portability assessment fails or the bank imposes an unacceptable reprice, and it avoids a last-minute scramble that could lead to a delayed settlement and penalty interest under the sale contract.