The legal protection described here is United States federal law, and it does not cover everyone. Who it leaves out is on its own screen, because that matters more than the rule. Canada is different: protection there comes from provincial rules, which vary. This is general information, not advice about your own workplace.
You do not discuss your salary with colleagues. Nobody wrote it down, nobody taught it, and almost everyone follows it.
Where did it come from?
In the US, can an employer forbid staff from discussing their pay with each other?
The law protects employees acting together over wages, benefits and conditions. Comparing pay is exactly that.
Acting alone can still count, if you are trying to get colleagues to act together or speaking on their behalf.
One person raising it for the group is not outside the protection.
A written rule does not have to be enforced to be unlawful. If employees could reasonably read it as discouraging them from discussing pay, that is enough.
The chilling effect is the violation.
This protection comes from one Act, and that Act does not define everyone as an employee.
If you are outside it, none of the above applies to you.
Which of these are covered by that federal protection?
Tap an item, then a bucket
Agricultural labourers. Domestic workers in a home. People employed by a parent or spouse. Independent contractors. Supervisors. Workers under the Railway Labor Act. And public-sector employees at every level of government.
Several of those groups are among the lowest paid and least secure.
The protection is real, and it is thinnest where pay secrecy costs most.
Many people promoted to supervisor do not realise they stepped outside this protection on the same day.
And whether you count as one depends on your actual duties, not your job title.
Because it is self-reinforcing. Nobody talks, so nobody learns it is allowed, so nobody talks.
The silence is the mechanism, not the policy.
Information about pay is worth something in a negotiation, and it is worth more to whoever has it.
If only one side of the table knows the range, the range is not really a negotiation.
Several US states and Canadian provinces now require employers to publish a pay range in job postings.
The list is changing, so check the rule where you are rather than trusting a list written today.
The rule against discussing pay is usually a habit, sometimes an unlawful policy, and occasionally a real gap in your protection.
Which of the three it is, is worth knowing before you decide to follow it.