In granular analysis, we show the rate offer moves lower for savers have been faster than for borrowers. But the size of the shift might surprise you, with at least 3 interesting out-takes from this analysis

If you are like us and had the feeling banks have been lowering fixed home loan rates slower than their term deposit rates, as the Official Cash Rate (OCR) has fallen and wholesale interest rates have declined with them, then you might be right.

But what might surprise you is the variation over all of 2025 isn't a lot.

We decided to test the feeling with some data. Our data summary is set out below.

Even though the data below is a lot, it is merely a summary of our raw data resources. We encourage readers to inspect these summaries and report what you find interesting.

What we did to make this data easier to analyse was to average the popular 3, 6 and 12 month term deposit (TD) rates at each month-end, and compare that with the average 6, 12 and 24 month fixed home loan rates. We did this for all the five main banks. This is a generalised comparison, one far from what bank treasurers do and far from how banks actually make rate decisions. It ignores wholesale money costs. But from an outsider's perspective it sort of makes bush sense, and allows us to compare each of these big five banks on the same basis.

What we found interesting was:

1. Overall, the big five banks have padded their margins by a bit more than +10 basis points (bps) so far in 2025. This was less than what we expected to find.

There were some quite wide variations between banks, however. For example, Westpac and ASB gained almost +20 bps, whereas BNZ moved both TD and mortgage rates at almost the same pace.

2. On the term deposit front, all banks started the year with almost identical rate offers. But by October, some variation had crept in. Kiwibank is now offering better rates in this zone than others, BNZ and Westpac are a bit lower, and ANZ and ASB are now the laggards.

3. On the home loan front, Kiwibank and Westpac started the year with a small rate advantage in their carded offers, but by October those had vanished with all banks remarkably aligned. If there is competition, it is away from the carded rates, in the customer app offers and perhaps from 'specials' only pushed via mortgage broker channels. And of course, the cashback offers come into play as well and these are not reflected in carded rates, of course.

We did this comparison on the basis of data we have and just for the big five banks who account for close to 90% of all banking in the country.

But we should note that from July this year, the Government has stepped up to guarantee customer deposits to a $100,000 level at all the institutions covered by the DCS (Depositor Compensation Scheme). And that is all banks and many non-banks.

So the risk to savers is essentially zero if your total exposure at any of these institutions is $100,000 or less. That means savers have the risk-free opportunity to avail themselves of higher returns at other than their main bank. And it also removes risk from depositing at many local community-owned or community-minded institutions. You can now "support local" without taking any risk to your capital.

Here is our granular data summaries which inform the preceding commentary and analysis.

We encourage your feedback in the comment section below, although you will first need to be a supporter to do that.