Alphabet Inc.'s Google LLC has issued new remote-work guidelines as part of an accelerated plan to gradually get employees back to the office.

Google was one of the first big U.S. companies to send employees home to work as a result of the coronavirus. Now, it is on track to be among the first to bring them all back again.

According to an internal memo, Google expects all of its staff members to be back in the office by September. In the meantime, the company will reopen some U.S. offices. Workers have been asked to return on a volunteer basis ahead of the September deadline.

The memo said several U.S. offices will be opened in a limited capacity this month. Reopenings will depend on location, availability of vaccines and COVID-19 cases.

"It's now been a year since many of us have been working from home, and the thought of returning to the office might inspire different emotions. The offices won't look exactly the way you remember them, but our amazing REWS teams are doing their best to make them comfortable, including providing meals, snacks and amenities where possible," Google's head of people operations Fiona Cicconi said in an internal email.

The email sent Thursday advised employees to get vaccinated. Cicconi said vaccination isn't mandatory but is advisable for those who plan to return to offices.

Employees who don't want to return after September have been told to submit applications. Cicconi said the company would permit workers to work from home for up to 12 months on a case-by-case basis. After Sept. 1, all other employees will be required to show up for at least three days a week.

Google will remain vigilant in preventing infections, it said.