Buying art at Sotheby’s has become more expensive as the top international auction house increased its buyer’s premium, the rates it charges a successful bidder.

As of last Sunday, anyone who purchases a work of art has to pay 25 per cent to the auction house on the first $200,000 of the hammer price, compared with the earlier threshold of $100,000.

Above $200,000 and up to and including $3 million the rate is 20 per cent, a rise from the earlier range of $100,000 to $2 million.

For the remainder of the hammer price above $3 million the charge will be 12 per cent, compared with $2 million under the previous rate structure that has been in place since 2013.

Bill Ruprecht, the chairman and president of Sotheby’s, said the changes were needed to boost the New York-based auction house financially.

“This will improve Sotheby’s revenue, strengthen the company’s profit margins, fund innovation, help us continue to make interesting and exciting investments in the business, and support our growing online and traditional engagement with clients around the world,” Ruprecht said in a statement.

Sotheby’s main competitor, Christie’s, owned by French luxury-goods magnate François Pinault, last raised its rates two years ago. A spokeswoman said it had no plans to follow the example of Sotheby’s, a publicly traded company.

Privately owned British auction house Bonhams said it also has no plans to change its premiums.