The government wants to let Inland Revenue chase owed tax and give out tax refunds without people having to file a tax return.
The proposal covers taxpayers whose only income comes from a salary, wages or investments.
Prime Minister Bill English said the changes would make the tax system fairer and simpler, benefiting about 3 million people.
"It's very difficult for people to get it right, with the best of intentions.
"And the effect of that, particularly around family tax credits, is that a significant proportion don't claim and therefore don't get the entitlement because of the risk that they might end up being overpaid and having to pay money back," he said.
Mr English said the changes would also save time and money correcting errors in people's tax returns.
The changes will go out for consultation until 28 July.