Generally, these contracts will be made available through a tender process. If the value of the work is less than a certain amount (in my locale it is $65000) t

Generally, these contracts will be made available through a tender process. If the value of the work is less than a certain amount (in my locale it is $65000) then you can circumvent the tender process and sell directly to the government. In practice, a large IT provider may have been awarded a contract through tender to provide all technical services, and they will then subcontract to other vendors (such as yourself). This can be a good way to circumvent onerous vendor requirements that may be attached to the customers tender process.