Calculating Bank Net Interest Income and Net Interest Margin

Summary

The document explains how to calculate net interest income (NII) and net interest margin (NIM) from bank financial statements. NII is interest income minus interest expense, representing the income earned on assets after their funding costs. The example gives interest income of 35 and expense of 21, producing NII of 14.

NIM expresses that net interest income relative to the bank’s assets. The response notes that beginning assets can serve as a simple denominator, while average assets over the period are presented as the professional standard. Using beginning and ending assets of 645 and 673 gives average assets of 659; dividing NII by that average yields a margin of 2.12%. The exchange corrects the questioner’s proposed calculation based on net income and total assets. It is a brief accounting explanation, and the example does not address differences in reporting conventions or adjustments that may apply across institutions.

Key ideas

• Net interest income equals interest income minus interest expense.
• Net interest margin relates net interest income to a measure of the bank’s assets.
• Average assets during the period are presented as the preferred denominator for NIM.
• The example uses average assets of 659 to calculate a margin of 2.12%.

Tags

# Calculating the net interest income and net interest margin


# Calculating the net interest income and net interest margin












The tabel below contains financial statement information from the CBA 2013 annual report.

I am asked to find the Net interest income and net interest margain:

My answers are as follows:

Net interest income = interest income-interest expense =35-21=14

Net income margin = (673-632)/673.

I'm not sure how to calculate net income margin, but would anyone be able to verify whether my answers are correct or not.

## Answer by nbbo2 (score 1)

https://quant.stackexchange.com/a/29795

You are a bank (or a bank like institution) that makes money from a portfolio of assets (such as loans) which are financed by liabilities (such as deposits or interbank loans).

The Net Interest Income is how much you make on your assets after subtracting your cost of financing those assets, so we have 35-21 = 14.

Your Net [Interest] Income Margin is how much money you make through this process expressed as a percentage of assets. How to measure the assets? A simple approach is the assets at the beginning of the period, i.e. 645. However I believe the professional standard is the average assets during the year which would be (645+673)/2. We would then have NIM = 14/659 = 2.12%

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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.