Seattle: Starbucks is ramping up its return-to-office mandate, requiring more corporate employees to be physically present at its headquarters and urging some to relocate to Seattle or Toronto. In a letter to employees on Monday, Starbucks Chairman and CEO Laxman Narasimhan said corporate staff must work four days per week in the office starting early October, up from the current three days. In a significant shift, all corporate people leadersa broad category including managers and abovem