Senior IT professionals claim efforts to upgrade to Office 365 are being hampered by a requirement to use the latest software on-premise.

Sources from a large organisation recently told CBR that Microsoft requires them to upgrade their on-premise solutions to the latest available version minus one in order to use Office 365.

It will not let them access earlier versions of applications on its cloud solution, despite their on-premise applications being too old to upgrade to the latest available software without huge cost implications.

The tech giant is allegedly forcing them to subscribe to either the latest versions on 365 or the versions immediately preceding those.

However, our sources, who work for a high-profile organisation and wish to remain anonymous, claim the gap between their on-prem software and the latest available on 365 is too wide to jump.

The news comes shortly after Microsoft announced the release of Office for iPad, which got 12 million downloads a week after its release on the App Store.

Microsoft’s Office apps are free to download in order to just view files, but subscriptions to the 365 solution start at $100 a year for Office Home Premium, which grants a user access on five computers or mobile devices.

As a cloud service, Office 365 updates its software automatically, including security updates and major releases.

Microsoft did not deny the claim that it requires customers to deploy the latest available versions of 365, but insisted that it remains a "great value for money" service.

A spokeswoman said: "An increasing number of businesses are recognising the potential benefits Microsoft Office 365 can bring to their organisation.

"There is a low up-front cost as Office 365 is available as a low-cost monthly subscription. The fact that Office 365 can be accessed across a range of devices gives businesses the opportunity to get great value for money from their subscription."

While businesses continually face the issue of upgrading on-premise software, many are currently trying to deal with the issue of migrating from Microsoft’s aged operating system, Windows XP, which still contributed to 27% of all web traffic in March.

Support is due to expire for the 13-year-old OS tomorrow, and businesses are looking at options ranging from virtualisation to migrating to Windows 7 or 8.

The government struck a £5.5m deal last week with Microsoft to secure custom support for public sector computers still running XP, including around a million NHS PCs and 34,000 Metropolitan police desktops.

Analayst house CIC recently told CBR that for many companies, the cost of upgrading could outweigh the cost of custom support, depending on the size of their infrastructure.

Microsoft’s spokeswoman said: "Many organisations have made good progress in moving to a modern desktop operating system and have successfully mitigated the risk that running Windows XP will bring. However, some organisations will not have moved off Windows XP by this date.

"We have made an agreement with the Crown Commercial Service to provide eligible UK public sector organisations with the ability to download security updates to Windows XP, Office 2003 and Exchange 2003 for one year until April 8 2015. Agreements such as these do not remove the need to move off Windows XP as soon as possible."