The nudity website it runs is currently not accessible from a UK IP address., and documents on Companies House show Itai Tech Ltd recently applied to strike itself off the UK register of companies.
Ofcom said its fine accounted for the company's decision to make its site unavailable to UK users, which it said occurred shortly after the investigation started in May.
"The use of highly effective age assurance to protect children from harmful pornographic content is non-negotiable and we will accept no excuses for failure," said Suzanne Cater, director of enforcement at Ofcom.
"Any service which fails to meet their age-check duties under the Online Safety Act can expect to face robust enforcement action, including significant fines."