Taxpayers who earn £1 million a year would be forced to make their tax records public under a Labour government, shadow chancellor John McDonnell has said.
In an interview with The Guardian, Mr McDonnell said greater transparency in individual tax affairs would deter avoidance.
He said Labour is drawing on the example of Scandinavian countries such as Norway and Sweden, where the practice is common.
"There is a big issue now about, people don't have trust in the establishment - they don't think they're listening to them, don't think they're paying their way or being fair," he said.
"So one way of re-establishing some element of openness and transparency would be, why not - over a million, you publish your tax return. Why not?"
He said the move would help restore trust in society, while reducing tax evasion and avoidance would help ensure public services were more generously funded.
"The first thing is making sure that tax avoidance and tax evasion are tackled properly; and the second issue is making sure that you invest rather than give it away," he said.
"At the moment we're getting the worst of all worlds - they don't collect it; they don't tackle it; and at the same time what they do collect, they give away."
Mr McDonnell is also warning Chancellor Philip Hammond he must come up with extra money for social care and the NHS when he delivers his first Budget next week.
In a speech in London, he will say the Government's plans do not come close to addressing the scale of the crisis facing the NHS.
He will warn Mr Hammond he cannot continue to claim credit for improving economic growth figures while leaving health and social care without the funds they need.
"The experience on the ground of patients, doctors and nurses is of a treasured institution already drifting into the greatest crisis in its history," he will say.
"Current plans from the Government do not come anywhere close to addressing the scale of the crisis, even in an optimistic scenario.
"It is essential that they now bring forward plans to close the funding gap if we do not want to lose our NHS."
He will add: "The Chancellor cannot kick the can down the road any longer, or perform a Jekyll and Hyde routine, in which he pretends that he cannot give the proper funding our NHS and social care desperately needs, while at the same time boasting better growth forecasts in the economy."
Mr McDonnell will also call on the Chancellor to end the "discrimination" which had seen cuts to public services "disproportionately" affect women.