The intended price rise comes at a bad time for the Government, given a major effort in Whitehall to reduce IT spending as part of a wider focus on civil service costs.
The price rise will only apply to new purchases, rather than ongoing contracts, and Microsoft said it would not increase prices for consumers.
However, the rise is likely to deal a blow to businesses, which may have to raise IT budgets or sacrifice other projects in order to pay for the increased charges.
In its accounts, Microsoft does not strip out UK revenues but they are believed to amount to billions of pounds each year.
Last week, the Seattle-based technology giant reported quarterly sales of $20.5bn (£16.8bn).
Softcat, the British IT reseller, said last week it had seen several foreign suppliers raise prices, which it had been forced to pass on to consumers.
Microsoft said what it called “harmonisation adjustments” were similar to those it made to pricing in Norway and Switzerland, after movements in the krone and Swiss franc earlier this year.
A Cabinet Office spokesman said: “We are constantly monitoring market and supplier pricing to ensure best value for our customers and the taxpayer. Where we are made aware of proposed price changes we will work closely with that supplier to identify ways to mitigate any increases in price.”