Microsoft is officially charging customers at least $600 per server to safely run Windows Server 2003 after its July 14 support cut-off date.

The number has come to light from Microsoft licensing expert Paul DeGroot of Pica Communications, who told The Reg he knows customers who’ve been quoted this figure.

The price is for the first 12 months following the July 2015 cut off and will double every year afterwards that a customer on a special custom-support deal continues to run Windows Server 2003.

It’s the first actual, public figure that’s been attached to Microsoft custom support agreements Windows Server 2003.

It is three times the charge made for a custom-support deal for those running Windows XP after that operating system’s end-of-support deadline last year.

One SI, meanwhile, has told The Reg that he has a number of big clients who will miss the July date and who have also talked to Microsoft about custom support deals.

One running several thousand Windows Server 2003 machines will pay “high single-digit millions” for the first year and "high double digit millions" in year two, our source - who wished to remain anonymous - said.

These aren’t the only people who look set to pay Microsoft big bucks to continue using the legacy server operating system after the July cutoff.

July 14 is when extended support for Windows Server 2003 ends, meaning no more security fixes or updates to new vulnerabilities, hacks or viruses.

An AppZero survey of 500 Fortune 1,000 IT pros found 47 per cent still unaware of the end-of-support date or lacking plans for remediation.

A quarter had more than 500 machines running the 12-year-old operating system. According to AppZero, ERP and CRM dominate.

The only hope is that Microsoft compromises on price, as the deadline approaches and major customers continue to run sensitive mission-critical applications.

Customers in regulated sectors, like banking and health, where they are fined for taking actions that put customers’ details and data in danger will carry most weight.

Also, the greater your number of servers the bigger discount you can extract from Redmond.

DeGroot told The Reg that Microsoft offered discounts of up to 90 per cent on the quoted Windows XP custom-support price. That might tempt some customers to hold out for a similar deal on Server 2003 custom support as the deadline nears.

Microsoft refused to comment on the $600 price. In a statement, the company said simply custom support prices vary depending on “specific customer needs.” ®