APS 117 is the Australian Prudential Regulation Authority’s (APRA) prudential standard governing how authorised deposit-taking institutions (ADIs) measure and manage interest rate risk in the banking book (IRRBB). It sets out the specific calculation methods, capital requirements, and reporting obligations that banks must follow to ensure they hold adequate capital against potential losses arising from changes in interest rates. This article walks through the key questions Australian banks are asking about APS 117 right now — from who it applies to and how it connects to global Basel standards, through to the practical compliance challenges and how to get your systems ready.

What does APS 117 actually require banks to calculate?

APS 117 requires Australian banks to measure the interest rate risk embedded in their banking book positions and hold regulatory capital against it. The banking book includes loans, deposits, fixed-income securities, and other non-trading exposures whose value and earnings are sensitive to changes in market interest rates.

The standard covers several core measurement areas. First, banks must quantify the impact of interest rate movements on their economic value of equity (EVE) — that is, how the net present value of their banking book assets and liabilities changes when rates shift. Second, they must measure the effect on net interest income (NII), capturing how rate changes flow through to earnings over a defined horizon. Third, they must apply prescribed interest rate shock scenarios and assess their capital position under each.

Beyond the headline sensitivity figures, APS 117 also requires banks to identify and measure specific sub-risks within IRRBB, including repricing risk (mismatches in the timing of rate resets across assets and liabilities), yield curve risk (non-parallel shifts in the rate curve), basis risk (exposure to different reference rates moving independently), and optionality risk (embedded options such as loan prepayment or deposit withdrawal features). Each of these contributes to the overall IRRBB capital requirement.

Which Australian banks does APS 117 apply to?

APS 117 applies to all APRA-regulated authorised deposit-taking institutions in Australia, including the major banks, regional banks, foreign bank branches, and other ADIs that carry interest rate risk in their banking books. In practice, every institution that takes deposits and makes loans — which describes virtually every ADI — carries some degree of IRRBB exposure.

APRA distinguishes between different tiers of ADIs in terms of the sophistication of measurement approaches available to them. Larger, more complex banks are expected to use more advanced internal measurement systems, while smaller ADIs may apply simpler standardised approaches. Foreign bank branches operating in Australia are also subject to APS 117 for their Australian operations, though APRA may apply modifications depending on the home regulator’s framework.

For smaller ADIs with straightforward balance sheet structures, the practical burden of APS 117 may be more limited. However, any institution that offers fixed-rate mortgages, term deposits, or other products with embedded rate sensitivity needs to understand its obligations under the standard. The threshold is not purely about size — it is about the nature and complexity of the institution’s interest rate exposures across its banking book.

How does APS 117 align with Basel international standards?

APS 117 is APRA’s domestic implementation of the Basel Committee on Banking Supervision’s IRRBB framework, which was substantially updated in 2016 and further refined as part of the broader Basel III and Basel IV (also called Basel 3.1) package. The Basel Committee’s standards require banks to measure IRRBB using both EVE and NII metrics across a defined set of interest rate shock scenarios, and APS 117 reflects these requirements closely.

The alignment is intentional. APRA designed APS 117 to keep Australian banks broadly consistent with international peers, which matters particularly for banks that operate across borders or are subsidiaries of global banking groups. Where APRA has made adjustments, these typically reflect the regulator’s preference for prudential caution rather than departures from the Basel framework’s underlying logic.

One area where the connection to the broader Basel IV framework is especially relevant is the interaction between IRRBB and Pillar 2 capital requirements. Unlike credit risk or market risk — which carry explicit Pillar 1 minimum capital charges — IRRBB sits primarily within Pillar 2 under the international framework. APRA, however, has taken a more prescriptive approach, requiring ADIs to hold capital commensurate with their measured IRRBB exposures and to demonstrate that their internal governance and risk appetite frameworks are adequate. Banks working through APS 117 compliance are therefore often doing so as part of a wider Basel 3.1 implementation programme that also touches APS 110 (capital adequacy) and APS 111 (capital measurement).

What methods can banks use to measure IRRBB under APS 117?

Under APS 117, Australian banks can use either a standardised framework or, with APRA approval, an internal measurement system (IMS) to quantify their IRRBB exposure. The choice of method affects both the complexity of the calculation and the resulting capital assessment.

The Standardised Framework

The standardised framework is the baseline approach for ADIs that have not obtained APRA approval to use an internal measurement system. It applies prescribed interest rate shock scenarios — including parallel shifts, steepeners, flatteners, and short-rate shocks — to the bank’s repricing cash flows and calculates the resulting EVE and NII sensitivities. While less tailored than an internal model, the standardised framework provides a consistent, comparable basis for APRA to assess IRRBB across the industry. Banks using this approach must still invest in robust data infrastructure to produce accurate repricing schedules and behavioural assumptions for products such as non-maturity deposits.

The Internal Measurement System (IMS)

The IMS allows banks to use their own approved models to measure IRRBB exposures, incorporating institution-specific behavioural assumptions, product features, and hedging strategies. This typically produces more precise sensitivity estimates for complex balance sheets and can better reflect the actual risk profile of the institution. However, IMS approval requires significant investment in modelling infrastructure, validation, and ongoing documentation. APRA’s approval process is rigorous — banks must demonstrate that their models meet strict standards for accuracy, governance, and integration into day-to-day risk management and decision-making.

What are the biggest compliance challenges banks face with APS 117?

The biggest compliance challenges with APS 117 centre on data quality, modelling complexity, and the operational demands of keeping up with ongoing regulatory updates. Banks that previously relied on simpler approaches to IRRBB often find that APS 117 requires a far more granular level of product-level and cash-flow-level data than their existing systems were built to handle.

Data readiness is consistently the first obstacle. APS 117 requires accurate, timely inputs at the individual product and contract level — including repricing dates, notional balances, embedded options, behavioural assumptions for non-maturity deposits, and hedging instrument details. If this data lives in multiple systems or is subject to reconciliation gaps, the EVE and NII sensitivity calculations will be unreliable and the audit trail incomplete. This is where BCBS 239 principles around data aggregation and reporting accuracy become directly relevant to IRRBB compliance.

Behavioural modelling is a second major challenge. Products such as non-maturity deposits, fixed-rate loans with prepayment options, and revolving credit facilities do not have contractual repricing dates that can simply be fed into a cash-flow model. Banks must develop and validate behavioural assumptions — for example, the expected repricing behaviour of at-call savings accounts — and these assumptions must be defensible to APRA and consistent with the bank’s observed customer behaviour. The Basel Committee’s 2016 IRRBB standards provide guidance on the boundaries for these assumptions, and APRA expects ADIs to stay within them.

Calculation transparency is a third challenge. Regulators expect banks to explain their IRRBB numbers at a granular level — not just report the top-line EVE sensitivity figure. Producing drill-down analysis from the aggregate capital impact back to individual product and cash-flow contributions requires a calculation engine that preserves full traceability, not just a summary output.

Finally, keeping up with regulatory change is an ongoing pressure. APRA periodically updates its prudential standards in response to Basel Committee guidance, and banks need systems that can absorb parameter changes and recalibrate quickly without requiring lengthy IT development cycles.

How should banks prepare their systems for APS 117 compliance?

Preparing your systems for APS 117 compliance starts with consolidating your IRRBB data into a single, well-governed data environment before you attempt to run calculations. Banks that try to build their IRRBB measurement layer on top of fragmented data sources typically spend more time reconciling inputs than improving their risk management.

A few practical steps make the biggest difference:

• Centralise product-level and cash-flow data: Bring loans, deposits, securities, and hedging instrument data into one financial data repository with clear data quality scoring and automated reconciliation. This directly supports the BCBS 239 requirements that underpin APS 117 reporting.
• Implement EVE and NII calculations with full traceability: Your calculation engine should link every sensitivity output back to the underlying product, cash flow, and behavioural assumption inputs. Regulators and internal audit teams will expect this level of drill-down.
• Build scenario and stress-testing capability: APS 117 does not exist in isolation. IRRBB exposure interacts with your credit risk RWA, your liquidity framework, and your overall capital adequacy position under APS 110. Systems that let you run what-if analyses across these risk types give you a much clearer picture of your capital position under stress.
• Treat regulatory calculations and reporting as separate disciplines: Your IRRBB calculation engine should produce clean, auditable results that can feed into whichever regulatory reporting tool your institution uses. Keeping the calculation layer independent of the reporting layer gives you the flexibility to update either without disrupting the other.
• Plan for ongoing change: Configure your system so that parameter updates, new regulatory scenarios, and revised APRA guidance can be applied by your risk team directly, without IT involvement for every change.

At ElysianNxt, our Basel.NXT module is built around exactly this approach, covering IRRBB, liquidity, and the full credit risk framework with real-time calculations, contract-level traceability, and a UI-driven configuration layer that puts your risk team in control. Banks across Asia Pacific and Europe have used it to go live with Basel IV compliance in a fraction of the time and cost of traditional solutions, and the same platform covers liquidity risk, counterparty credit risk, and leverage ratio so your entire Basel framework runs in one place.

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