LONDON — Lawmakers on the island of Jersey have approved scrapping a decades-old law that prevented married women from talking to the tax authorities without the permission of their husband or filing taxes under their own names, a mechanism described by a local senator as “archaic.”

Jersey, a small island in the English Channel a few miles from the French coast, is a dependency of the British crown but is by and large independent of Britain, with its own directly elected assemblies, fiscal system and courts.

That distinction has made Jersey a popular tax haven, but its financial laws have not always kept up with the times: Under its current tax law, introduced in 1928, only the husband in a heterosexual marriage can pay taxes, with his wife’s earnings considered part of his income. She has needed his permission to be treated separately or even to discuss her financial affairs with the tax office.

Things became a bit more modern in 2013, when a box appeared on income tax forms that husbands could tick rather than giving written permission.

When civil unions and same-sex marriages became legal on the island, the law allowed the older partner to take the role of “husband” and the younger “wife.”

Under the proposal backed by a majority of lawmakers on Tuesday, taxpayers would be considered as individuals. The legislation was introduced in November by Susie Pinel, the island’s treasury minister, who vowed to provide similar rights and responsibilities to all residents in their tax affairs.

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“It will remove the archaic presumption in the current law that a wife’s income is deemed to belong to her husband,” Ms. Pinel said in a statement released before the vote.

Sam Mézec, another lawmaker, said that would put Jersey where it should have been for decades.

“It’s simply wrong that in the year 2020 our tax law erases the identity of married women,” Mr. Mézec said, according to British news outlets. “It’s the stuff of medieval times, not the modern age.”

Legislation to bring in the changes will be drafted later this year and should come into effect in 2021. The Jersey government said that starting in 2022, married couples and civil partners will share responsibility for joint tax affairs, unless they choose to file separately. Both individuals would be able to sign the tax form, and would have equal rights to manage taxes.