Plans requiring people to earn £38,700 a year before bringing family to the UK will be introduced in early 2025, Rishi Sunak has said.
The rise from the current £18,600 level was announced earlier this month and had been scheduled for the spring.
However, the government has rowed back and now says the increase will come in two stages.
Next spring, the threshold will rise to £29,000, with the further increase not applying until the following year.
Speaking in Lincoln, Mr Sunak defended the timetable, saying: "The principle here is absolutely right that if people are bringing dependants into this country as part of their family, they must be able to support them.
"We're doing exactly as we said we would. We're just doing it in two stages. So it will go up in a few months time and then it will go up again the full amount in early 2025."
He added: "The levels of migration are far too high. They've got to come down."
The next general election has to be held by January 2025, meaning Labour will face close questioning about its position on the proposed rules.
Official estimates indicate net migration - the difference between the number of people coming to and leaving the UK - rose to a record 745,000 in 2022.
In a bid to reduce the number, the government announced earlier this month it would be changing the rules for family visas alongside other measures including foreign workers having to earn at least £38,700 to qualify for a UK skilled worker visa.
Ministers had faced criticism that the increase from £18,600 to £38,700 for family visas was too high and would disrupt households.
The OceanNewsUK also understands there were concerns that changing it all at once could leave the government more vulnerable to legal challenges.
On Thursday, ministers announced the threshold would rise only to £29,000 in the spring before increasing to £38,700, but gave no further timetable.
However, on Friday Mr Sunak provided more details when he said the figure would rise to the full amount in early 2025.
A spokesman for former immigration minister Robert Jenrick, who quit the government earlier this month over Mr Sunak's approach to illegal migration, said the new visa rules "need to be implemented immediately".
"Otherwise there risks being a fire sale of visa applications" as people tried to enter the country under the current system, he added.
The Home Office has confirmed that anyone who wants to renew a family visa will be able to, without having to meet the new earnings threshold.
A government factsheet said those who already had a family visa within the five-year partner route, or who applied before the minimum income threshold was raised, would continue to have their applications assessed against the current income level.
Official statistics show that 82,395 family-related visas were issued in the year to September - 79% to partners, 13% to children and 8% to other relatives.
A policy document said the new £29,000 threshold could contribute a "low tens of thousands" cut towards the government's overall target of reducing legal migration by 300,000 this year.
Speaking to OceanNewsUK, Madeleine Sumption, director of the University of Oxford-based Migration Observatory, said £29,000 was still "quite restrictive" compared with levels in other European countries and that £38,700 was "unusually high".
Labour's shadow home secretary Yvette Cooper said the government had "failed to consult anyone on their new proposals and took no account of the impact of steep spousal visa changes on families next year, so it's no surprise they are now rowing back in a rush".
'It's affected me immensely'
Ruby told the OceanNewsUK the £29,000 threshold was too high and could stop her husband Furkan, who's in Turkey, coming to live with her in Plymouth.
She said: "[I'm] still £5,000 of short of what the requirement is now," despite already changing her job for the visa requirement - moving from being self-employed to a £23,000 a year job as a veterinary receptionist to show she has steady income to support her husband's visa application.
"I think it's cruel on so many approaches," she said. "When I first heard I was beside myself... to just change it has affected me immensely so much.
"I have lived here all my life, my family are here, I should be entitled to having a family life just like everyone else."
Cam has been with his American wife for four years and had been hoping she would be able to join him in London.
He earns £36,000 and had planned to make his application in March - after enough time to show he had a stable income - but was uncertain he would make it through before the new threshold came into force in the spring.
Responding to the government's decision to introduce the rise in stages, he told the OceanNewsUK: "On a personal level, it's a big relief knowing that even if [the income threshold] does change before we can apply, we'll still meet the requirements. Hopefully everything will be fine.
"However I know a lot of couples, a lot of families, will still be feeling a lot of stress and a lot of pressure because they still won't be able to meet those requirements."
British citizen Josie lives with her Italian husband in Ancona, Italy. The couple - both scientists - married in December 2020 and were planning on moving to the UK to settle.
Speaking to the OceanNewsUK's World at One programme, Josie said that despite the delay in introducing the £38,700 threshold, she was still not certain about returning to the UK.
"Given the flipflopping around of policy decisions, it doesn't give us much confidence - it is a shame because the UK is a great place to be as a scientist."
