Last time I discussed how the cash rate influenced the interest rate.  But what happens when the cash rate goes negative?  This is the focus of today’s post.

After recent discussions about “negative interest rates” across Australasia I thought it would be useful to talk about how these rates appear mechanically at a high level (in terms of financial system operations).

In class (and Gulnara’s posts here) the motivation of why negative interest rates might be appropriate in a policy sense was raised.  Furthermore, she did a great job of noting that it is unlikely that negative rates will cause additional savings (as some have claimed) and so theoretically we can continue to think about our investment model with negative interest rates.

For this post we will assume that the central bank is trying to influence interest rates towards a level that will “close the output gap” or “push Y to its sustainable level” and achieve their inflation target, and it just happens that this interest rate is negative.

The wrinkle is that we achieve this negative interest rate through a settlement cash mechanism – so we need to ask, how do negative rates in settlement cash accounts translate into lending and actual interest rates?