Mentioning money is like foraging for mushrooms one variety is a gourmet delicacy while its closest relative is lethal. When it comes to financial matters, we seem happy to share what we paid for our car, but not our house. The price of an air ticket is fine, but not the cost of the whole vacation. A killing on the stock market is broadcast; a cost of living increase is kept under wraps.

The amazing thing is that somehow most of us develop a nose for knowing how far to go without blundering into impertinence. We even sense when to go low “This entire system only cost me $200!” - or high - “The wine started at $25.00 a glass”. What subtle rules govern these fiscal conversations? And why is there such a strong taboo against declaring or enquiring about something as fundamental as income?

The answer might lie in the nakedness of income. Income is the body underneath the clothes of houses and cars. While there’s still a mystique about our earnings, we can dress them up as we like show a bit of cleavage or camouflage an unsightly bulge. In conversational terms, quizzing someone about their salary is only a step or two above asking them to “get their kit off”. It strips them of their ability to control how they’re seen.

Knowledge of somebody’s income also invites us to scrutinize their spending, whether we voice it or not. Can she really afford that on her salary? I don’t see why he doesn’t pay someone to do his gardening with what he makes! If others know our earnings are low, we may be letting ourselves in for uncomfortable offers of charity or disapproving looks for the occasional splurge. If they know we have more than adequate resources, we can face unwanted pressures to lend, spend or pick up the tab.

The idea that revealing our income somehow makes it public property and opens our financial habits up to others’ judgment and interference could explain why there’s less of a taboo on discussing what you used to make or what you might be able to earn in future. It’s tends to be one’s present state of affairs that stays shrouded in secrecy.

Purchases, bonuses, wins on the lottery, investments and bargains may all give clues to an individual’s income. But they also tell us about the person’s choices, values, tastes, skills and accomplishments. Income is far less personal; it concerns only money and economic status. Perhaps this is one guideline for understanding what is and isn’t acceptable to discuss when it comes to money matters. The conversations which flow most easily are those where people are exchanging information for a purpose other than “placing” each other.