The US government is deepening its commitment to open source principles, proposing that federal agencies share software tools and release their code to developers.

By the start of July, all federal agencies will be required to release at least 20 per cent of the software they have had specially developed.

While 20 per cent is the minimum requirement, agencies are "strongly encouraged to publish as much custom-developed code as possible to further the Federal Government's commitment to transparency, participation, and collaboration".

"This collaborative atmosphere makes it easier to conduct software peer review and security testing, to reuse existing solutions, and to share technical knowledge," the paper, titled Federal Source Code Policy - Achieving Efficiency, Transparency, and Innovation through Reusable and Open Source Software, read.

The proposals refer to third-party code, as software developed in-house is designated as public domain by default.

The government is also attempting to encourage greater collaboration between agencies, by making them share software with each other. The policy is intended to eliminate some of the federal government's $9 billion annual software spend.

Under the new proposal, agencies will require the delivery of the full source code - as well as all documentation and distribution rights - for any software it commissions, which can then be re-used across the federal government.