The inquiry was sparked after the discovery of a potential breach of treasury confidentiality by former PwC partner Peter Collins, who has been referred to federal police to investigate the allegations.
Finance department officials told the committee all Commonwealth contracts had conflict-of-interest clauses and required people who accessed sensitive data to sign confidentiality arrangements.
Deputy secretary Andrew Danks said unauthorised information sharing would trigger a breach, but departments needed to take a "contract management approach" to find out if this had occurred.
"We can't go into every consultancy to see who has got our information," he said.
"But if we do find out that things have been released or confidential information has been breached, that's where we have the termination clauses in contracts to consider."
The committee considered publishing the names of the 72 PwC staff involved in the recent scandal but ultimately decided against it.
Greens senator Barbara Pocock said there was a strong public interest in naming those involved.
"Australians are outraged at what has gone down inside PwC and my inbox is full of requests to keep pushing for the release of the names of all those involved," Senator Pocock said.
"Anyone doing business with PwC needs to be fully aware of who was involved and the roles that they played in devising and marketing the multinational tax avoidance scheme."
Finance Minister Katy Gallagher wants the public service to ease its reliance on consultants.
"We saw a shift towards outsourcing public service jobs into the private sector," she told ABC Radio on Wednesday.
"Obviously, the issues with PwC have highlighted that at an extreme end, but we've got a lot more to do to rebalance the public service (and) to make sure it's there as the important institution that it was always intended to be."
The committee is investigating the integrity of other consultancy firms which secure government contracts worth billions every year.
Consultants from audit, tax and advisory firm KPMG and treasury officials will be questioned.
In a submission to the inquiry, KPMG said integrity was at the core of its approach to its services.
The firm commissioned a review of its confidentiality processes which found policies and procedures were consistent with best practice.
"When government engages with us, we never take this trust for granted and we must, and do, take our responsibilities seriously," the submission said.
"Although we are confident in our policies and procedures as they relate to our confidentiality obligations ... we remain vigilant in regularly reviewing our operations to ensure they remain aligned with community attitudes and expectations."
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