Size excludes balconies and parking spaces.
Commuters who live away from home during the week are driving demand for small apartments, a spokesperson said. ING does not lend to foreign buyers.
There are high density suburbs where the deposits may be higher.
Apartments of less than 40 square meters remain unacceptable.
This is the second time in 14 months that ING has revised the underwriting guidelines for apartments and units with an interior surface area of less than 60 square meters.
Last year, he announced that those with interior space of less than 60 square meters – also excluding balconies and car space – and under the age of five will have a maximum loan-to-value ratio of 70%.
Apartments with interior space between 50 and 60 square meters – excluding balconies and parking space – and over five years old have a maximum loan-to-value ratio of 80%.
Citi, a division of the main US bank, is increasing minimum deposits by 15 percent for high-density apartments and those purchased directly from a developer or associated companies.
The loan-to-value ratios were reduced from 80% to 70% in July 2016.
Citi has a list of nearly 87 zip codes and 260 suburbs nationally designated as high density areas.
The bulk of postcodes can be found in Melbourne, Sydney, the surrounding suburbs and up to 15 kilometers from the central business districts.
It includes high-rise areas, such as Melbourne’s Docklands and the Central Business District, and extends to the inner suburbs of the inner ring where higher density apartment buildings are popular.
Citi reduces variable interest rates on principal loans by 10 basis points and interest rates for loans settled before May 1.
It increases variable interest rates for interest-only payments and line of credit products for loans also settled by May 1 by 30 basis points.
Both lenders offer products through mortgage brokers, who act as an intermediary between lenders and borrowers.
Christopher Foster-Ramsay, Director of Foster Ramsay Finance, a mortgage brokerage firm, said: “We are in an evolving credit market chasing owner, principal and interest occupied business with unprecedented demand. . “
Other lenders impose more stringent conditions on borrowers who seek multiple properties on separate titles located in the same block, or use multiple properties as collateral.
Firstmac, a non-bank lender with around $ 8 billion under management, tightened lending for apartments in developments over six stories, it excluded rental income as a service source from the mortgage.