Authorities have told SoftBank Group Corp. that it failed to declare income of some ¥93.9 billion ($875 million) from its tax haven-based units in the four years through fiscal 2015, sources close to the matter said Wednesday.

The telecommunications giant has paid an additional tax of some ¥3.7 billion including a penalty for understatement after its deficits were offset, they said.

"We have already submitted a revised report to the Tokyo Regional Taxation Bureau and have taken appropriate responses," SoftBank said.