Anything you say to a bank can be written down and used in evidence against you. Not by the bank so much as the Tax Department.
It is not confidential from the IRD. Always imagine an officer of the department is listening to your every word.
You have no control over the notes your bank manager makes of your meeting. Just in case he/she makes a mistake and writes a note of something he/she imagines was said, make a detailed diary note yourself immediately following the meeting.
For example, if you were to buy a property for renting and were to tell the bank there is a good capital gain to be made, this could be interpreted by the IRD as being a purchase made to get a capital gain. Consequence: taxable income.
If you have the intention to make a profit and a reasonable prospect of success, the eventual gain on any transaction you are engaged in is probably taxable. So, if you buy a rental property but have in mind selling it for a profit some time in the future, the profit on sale is taxable. On the other hand, if you buy the same rental property as a long-term investment to provide income in future years, you are not taxed on the profit you make on the eventual sale.
We all know property prices rise over time. So the person who buys to rent is aware there's likely to be a capital gain on sale of the property. The issue is you must buy for the income, not the capital gain.
The same applies to the sharemarket. Buy shares like Xero for fat dividends once they make profits and your sale of Xero shares for a gain is not taxable. Buy Genesis shares and sell them soon after issue “to take a profit” as sharebrokers say, and the gain is probably taxable.