Microsoft revealed last month that it’s planning to offer long-serving employees in the US the ability to voluntarily retire. While the terms of the buyout were supposed to be announced to employees tomorrow, sources at Microsoft tell me the company has posted them on its internal HR website a little earlier than expected.

US employees whose combined years of service added to their age totals 70 or more will be eligible for voluntary retirement, and the package will include five years of access to Microsoft’s healthcare coverage, a lump sum cash severance payment, and six months of vesting for unvested stock options.

The five years of medical, dental, vision, and well-being coverage will be fully subsidized by Microsoft for the first year, but employees who take the voluntary retirement option will have to pay a monthly premium for the remaining four years.

The lump sum cash payment will vary depending on employee levels. Those at Microsoft’s mid-senior level (level 64) will be offered a week of base pay for every six months of regular service, up to a maximum of 39 weeks. Those at more senior positions at Microsoft (levels 65–67) will be offered two weeks for every six months of regular service, up to the same maximum of 39 weeks.

Microsoft is also including six months of vesting for unvested stock options with this buyout offer, which will extend to 12 months if an employee has had 24 or more years of continuous service.

Around 7 percent of Microsoft’s US employees will be eligible for this buyout offer, which is roughly 8,750 employees. It’s the first time Microsoft has offered a voluntary retirement program in its 50-year history, and employees will have 30 days to decide whether they want to take the package or not.

Microsoft said last month that it will take a $900 million charge in its current quarter for this one-time program, which as GeekWire points out is roughly a day of revenue for the company.