San Francisco and Santa Clara counties eased guidelines that kept most office buildings closed for the last year except crucial security and support staff.
Now companies are allowed to open up a quarter of their offices, Big Tech companies are dragging their feet.
They say that they committed last year to allow workers to stay home until this summer or indefinitely said they stood by their timelines.
Some of this is based on their own analyses of public health data, other safety considerations and workers' preferences. Adopting vaccines, which in California are accessible to only the most vulnerable populations, is also a smaller factor.
Networking gear maker Cisco Systems Inc and file-storage service Dropbox Inc said their mandatory work from home policies would remain in effect until June, while Box Inc said its reopening is still scheduled for September.
Pinterest Inc is not eyeing a significant reopening until at least August, Alphabet Inc's Google until September and DocuSign Inc not before October.
Twitter, Adobe, PayPal Holdings, Twilio, Yelp and Zoom Video Communications Inc also will stay closed.