A90　 Seniority-based wages and performance-based pay systems are for full-time permanent employees, not non-regular employees such as temporary and part-time staff, whose salaries do not rise to reflect age and performance. According to surveys, the lifetime income of full-time permanent staff, who have worked from the age of 18 to 60, is 220 million yen. For non-regular employees it is only 57 million yen. Since the collapse of the economic bubble, companies have tried to hold down the number of full-time permanent employees and have increased the number of non-regular employ- ees. A survey, conducted by the National Tax Agency, shows that behind the eight years of falling annual incomes is the increasing number of non-regular employees. For these employees, becoming a full-time permanent member of staff is a huge step toward closing the income gap. But the route to permanent employment is a narrow one, and it is becoming increasingly hard to erase the differential.