A single Reserve Bank of Australia cash rate decision can move your monthly repayment before you even receive a letter about it. On a $600,000 variable loan, each 0.25% change adjusts repayments by roughly $90 to $100 a month. Understanding how that change actually reaches your mortgage, and how quickly, helps you plan around it rather than be surprised by it.
The path from the RBA to your repayment
The Reserve Bank sets the cash rate, which is the rate banks charge each other for short-term loans. It does not directly set your home loan rate. Instead, lenders use the cash rate as a reference point and adjust their own variable rates, which are influenced by the cash rate along with funding costs, competition, and each bank’s own margin decisions.
When the RBA moves the cash rate, banks typically announce a change to their variable rates within a week or two. Some pass on the full move, some pass on slightly less or slightly more, and timing varies between lenders. This is why two borrowers with the same loan size at different banks can see their new repayment take effect on different dates in the same month.
How your repayment is actually recalculated
Most lenders recalculate a variable rate loan repayment automatically once a rate change takes effect, based on your remaining loan term and outstanding balance. If you are on principal and interest, a rate rise increases both the interest and, in most cases, the total repayment amount required to still pay off the loan within the original term.
Does my repayment go up automatically, or do I need to request a change?
For most variable rate loans, the lender adjusts your minimum required repayment automatically and notifies you of the new amount. You generally do not need to request anything, though it is worth checking your loan statement or online banking after a rate change to confirm the new figure and make sure any linked direct debit reflects it correctly.
Borrowers on a fixed rate are shielded from this process until their fixed term ends. If your fixed period is expiring soon, it is worth checking well ahead of time what rate you would revert to, since revert rates are sometimes higher than the equivalent new customer variable rate at the same lender.
What an offset account or redraw does during a rate change
If you hold savings in an offset account, a rate change still applies to your full loan balance, but the interest charged is calculated on the balance after offsetting. A $50,000 offset balance against a $600,000 loan means interest is only calculated on $550,000, which softens the dollar impact of a rate rise in absolute terms, even though the percentage change is identical.
Redraw facilities work differently. Extra repayments sitting in redraw reduce your outstanding balance directly, which also reduces the dollar impact of a rate change, but funds withdrawn from redraw are treated as a new drawdown rather than a withdrawal from a separate account. The practical effect on repayments during a rate change is similar to offset, but the two products serve different purposes and are treated differently for tax if the property is ever used for investment.
Why the serviceability buffer matters even when rates fall
Lenders in Australia are required by APRA to assess new loan applications using a serviceability buffer of at least 3 percentage points above the actual loan rate. This means a borrower applying for a loan at 6% is typically assessed as though the rate were 9%, to check they could still manage repayments if rates rose further.
This buffer applies at the time of application, not to your repayments once the loan is settled. It exists to build a margin of safety into borrowing capacity calculations. If rates fall after settlement, your actual repayment falls with them, and the buffer used at application time has no further bearing on your loan, only on how much you were able to borrow in the first place.
What you can do ahead of a rate change
Reviewing your loan structure before or after a rate movement is often more useful than reacting to any single decision. Comparing your current rate against what new customers are being offered at your own bank, and against competitor rates, at least once a year can reveal whether refinancing or a simple rate negotiation makes sense.
Building a small buffer of extra repayments when rates are lower gives you more room to absorb a future increase without changing your budget significantly. A mortgage broker can model how a rate change of 0.25% or 0.50% would affect your specific loan and help you decide whether fixing part of your loan, switching lenders, or simply adjusting your budget is the most sensible response.
Key Takeaways
- The RBA cash rate influences, but does not directly set, your variable home loan rate, and lenders typically adjust within one to two weeks of a decision.
- Most lenders automatically recalculate your minimum repayment when a variable rate changes, without you needing to request it.
- Offset and redraw balances reduce the dollar impact of a rate change by lowering the balance interest is calculated on, though the two products are treated differently for investment tax purposes.
- Fixed rate loans are shielded from rate changes until the fixed term ends, and revert rates can be higher than new customer variable rates.
- APRA requires lenders to assess new applications at least 3 percentage points above the actual rate, which affects borrowing power at application time rather than ongoing repayments.
- Reviewing your rate at least annually and building a small repayment buffer helps you absorb future rate movements without disrupting your budget.