Buy-to-let landlords were left licking their wounds after a Budget that confirmed the suspicions of many that George Osborne was conducting an “outright assault” on the sector.

Landlords with more than 15 properties had been expecting to escape a three percentage point stamp duty surcharge on buy-to-let homes. But the chancellor instead declared that all buyers of additional homes would be subject to the levy, due to come into effect on April 1.

Alex Greaves, residential fund manager at M&G Real Estate, which is investing in large-scale “build-to-rent” homes, said the decision not to award an exemption for bigger investors was “clearly very disappointing”.

“We were fairly confident we were going to get it because of all the positive attributes you get from build to rent — in management, reliability, quality of service and the longevity that landlords can give to occupiers as well as the increase in the supply of much-needed housing.”

He said the move — combined with limits to mortgage interest tax relief from 2017 — would slow down the market in the short term by adding to costs. “These deals are so tight. When you put an extra percentage point on overall, it really does make it more of a challenge.”

But both he and Stephen Johnson, managing director of commercial lending at Shawbrook Bank, said long term investment in the sector would remain attractive in spite of an “unhelpful suite of changes” to the rules on buy to let announced in the past year. “We might see a slight pause but I don’t see it having a material impact on the investment thesis,” Mr Johnson said.

Those who buy a new main residence before selling their old one will pay the surcharge, but will then have 36 months — rather than the threatened 18 months — to claim it back if they subsequently sell their old main home. Multiple homeowners will also have three years’ grace between selling a main residence and buying another without facing the higher rates.

Those buying a home jointly with another person need to take care: even if one person owns no property but the other does, the purchase will be liable for the surcharge. By the same token, parents who wish to help their children to buy a home and are named on the deeds of their home will be considered as owners of additional property under the measures.

The new rules may also have implications for divorcing couples with families. Where a couple owns a house jointly and they divorce, a spouse who buys a local property to be close to the children will pay the extra unless he or she can first be bought out of ownership of the main residence.

Foreign buyers looking to buy a UK home may also be caught, even if it is their first or only home in the country. Mr Osborne’s measure is directed at boosting home ownership in the UK, but the Treasury said “property owned globally will be relevant in determining whether a property purchased in England, Wales or Northern Ireland is an additional property”.