Birmingham-based IT services group SCC has won a massive contract with HM Revenue and Customs.
The four year deal is potentially worth up to £560 million and will initially create 50 new jobs.
"We hope we will generate a lot more over the period of the contract, " said a spokeswoman.
It involves the delivery of supply chain management services across the entire technology infrastructure, HMRC being the third largest IT user of all Government sectors after the Ministry of Defence and Works & Pensions.
SEC already has a major contract with the MoD.
Chairman and chief executive Sir Peter Rigby said: "This is an important, high value new customer win for SCC, representing our most significant contract to date with one of the largest central Government departments in the UK.
"Continuing to generate significant growth opportunities in a challenging market, the business has secured this deal in the face of fierce competition.
"Underpinning SCC's success was our ability to demonstrate a thorough understanding of the complex organisational requirements of HMRC, combined with our superior end-to-end supply chain management skills, audio visual and e-business expertise."
Mark Forth, commercial director at HMRC, said: "Through this new partnership we will be able to deliver significant cost savings and process improvements. An essential aspect in awarding this contract has been the flexibility and commitment SCC has demonstrated in defining the best way we can work together to deliver real value and efficiencies."
HMRC was created by the April merger of the Inland Revenue and Customs and Excise.
SCC is a provider of IT services and solutions for European-based public and private sector organisations.
* Electronic Data Systems will pay the Government £71.25 million to settle a dispute over a faulty system the US computer services group supplied to administer a tax credit scheme. The dispute with EDS stemmed from technical problems when the system was launched in spring 2003. HMRC had threatened to sue the company after dropping it as its main contractor for information technology the same year.