Energy Shocks and Your Mortgage

Key takeaways

• Energy hits headline inflation first and underlying inflation second, if at all.
• Central banks look through a pure supply shock but not through second-round effects.
• Inflation expectations are the variable that decides which of those it is.
• Government rebates lower measured inflation temporarily, then unwind.

How does a supply shock become a rate rise?

The first-round effect is mechanical. Fuel and electricity are in the CPI basket, so when their prices jump, headline inflation jumps. That alone does not usually warrant a policy response, because raising interest rates does not produce more oil.

The second-round effect is the one that matters. Higher energy costs raise the cost of freight, manufacturing and agriculture, which shows up in the prices of goods that have nothing to do with energy. If workers then seek wage increases to recover lost purchasing power, and firms pass those costs on, a one-off price level shift becomes ongoing inflation.

That is what a central bank cannot look through. The judgement it makes - and it is a judgement, made in real time with incomplete data - is which of the two is happening.

What does the RBA watch to decide?

Expectations do most of the work. If people believe inflation will return to target, a price shock stays a price shock. If they begin to expect persistent inflation and act accordingly, it becomes self-fulfilling - which is why central banks talk so much about anchoring expectations.

What does a household actually do about it?

Not much about the shock itself, but the exposure is manageable.

• Model your repayment at a higher rate. The 3.0 percentage point serviceability buffer exists precisely because unexpected shocks happen; running the same calculation for yourself is free.
• Understand energy rebates cut both ways. Government electricity rebates lower measured inflation while they operate and lift it when they unwind, which can make the inflation path look better then worse without anything real changing.
• Do not restructure on a headline. A single quarter of elevated CPI driven by fuel is not a reason to fix a mortgage. The underlying measures are the signal.
• Reduce the energy exposure you can control - it is a real cost line whether or not the RBA responds to it.

Frequently asked questions

Why does the RBA raise rates when the problem is a supply shock?

It generally does not respond to the first-round price effect, which monetary policy cannot influence. It responds when the shock feeds into broader prices, wages and inflation expectations - the second-round effects that do become persistent inflation.

What does "looking through" a price shock mean?

Choosing not to respond to a temporary price move that will drop out of the annual inflation figure on its own. Central banks look through one-off supply shocks and respond to changes in underlying, persistent inflation.

Do energy rebates reduce inflation?

They reduce measured headline inflation while they operate, because household electricity costs fall. The effect is temporary - when the rebate ends, measured inflation rises again even though underlying price pressure has not changed.

Should I fix my mortgage after an energy price spike?

Not on that basis alone. Fixed rates are priced off market expectations that have usually already moved. Base the decision on how much repayment variability your budget can absorb rather than on a recent headline.

Related reading

• How the RBA Actually Sets the Cash Rate: The Reaction Function
• The 2026 Rate Reversal: How Three Hikes Undid a Year of Cuts
• Household Debt at 190% of Income: How Australia Compares

Sources

• Statement on Monetary Policy — Reserve Bank of Australia
• Consumer Price Index, Australia — Australian Bureau of Statistics