Goldman Sachs' US bankers have been ordered to disclose their Covid vaccine status ahead of a return to the office.
In a memo seen by the BBC, the investment bank said it was mandatory to do so by 17:00 BST on Thursday.
While it strongly encouraged staff to get a vaccine, it said: "We understand that the choice to get vaccinated is a personal one."
Goldman is hoping to bring US staff back to the office on 14 June, it told employees last month.
The notice, which was first reported by the New York Times, said: "Registering your vaccination status allows us to plan for a safer return to the office for all of our people as we continue to abide by local public health measures."
The bank had said staff in the US could work in the office without a mask if they had been vaccinated.
Its UK employees were also previously told that they should expect to be working on-site from 21 June - the date on which the government hopes to lift legal limits on social contact in England.
UK workers for the bank have not been told to report their vaccine status.
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But Kate Hindmarch, partner in employment law
at Langleys Solicitors, said that problems
may arise from requiring proof of vaccinations.
"Vaccinations create a conflict of legal protections, where the freedom of individual choice is weighed against the health and safety of others.
"Some employees may have a justifiable reason for not wanting to take the vaccine, and we would always urge employers to discuss an employee's reluctance, whether it be related to a disability or religious reasons."
She said there could also be serious ramifications if any employers dismissed staff who were reluctant to be vaccinated.
Goldman Sachs in particular has been vocal about a need to return to the office as social distancing restrictions ease.
"We know from experience that our culture of collaboration, innovation and apprenticeship thrives when our people come together, and we look forward to having more of our colleagues back in the office so that they can experience that once again on a regular basis," chief executive David Solomon, president John Waldron and chief financial officer Stephen Scherr said in a joint statement last month.
Mr Solomon also drew some criticism earlier in the pandemic when he described working from home as "an aberration".
Rival investment bank JP Morgan is planning for "significantly" less office space, it said in April. And big tech firms, such as Facebook, have said they will let all employees who can work away from the office do so once the pandemic is over.Goldman Sachs has told its UK bankers they need to be ready to return to the office in June.
That is the date on which the government hopes to lift legal limits on social contact in England.
While for many working from home has become normal, Goldman boss David Solomon previously described it as "an aberration".
But rival investment bank JP Morgan is planning for "significantly" less office space, it said in April.
Goldman bankers have in large part already returned to the office in parts of the Asia-Pacific region.
But, in India and Latin America "the devastating rise in the number of infections and deaths is leading to new lockdowns and significant strain", three Goldman top executives said in an internal memo on Tuesday.
However, the bank is "encouraged by the rollout of vaccines" in many places, chief executive David Solomon, president John Waldron and chief financial officer Stephen Scherr said.
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US bankers should be ready to come back into the office on 14 June, and UK bankers should make plans to be back on 21 June, they said."We know from experience that our culture of collaboration, innovation and apprenticeship thrives when our people come together, and we look forward to having more of our colleagues back in the office so that they can experience that once again on a regular basis," they said.
Staff who wish to continue to work from home should discuss this with their manager, they added.
While some bank bosses have indicated that working from home may not be a long term option for some employees, others are planning for smaller offices.
JP Morgan boss Jamie Dimon said in April that the investment bank will require "significantly" less office space in the coming years, needing just 60 seats per 100 people.HSBC boss Noel Quinn said at the end of April that the bank plans to move to a hybrid model of working, with employees having a mixture of working in the office and from home.
Some investment bank traders at Canary Wharf have been working from the office during the pandemic.
Barclays expects to keep a significant number of traders at Canary Wharf in the future.
Barclays boss Jes Staley has previously said home working is "not sustainable" for large financial institutions.
Bank employees in London and New York will be coming back into the office on a phased basis from mid-June, but the return to working from the office for Barclays employees will be gradual.
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