The entire HS2 program, including later extensions, was budgeted at $68 billion at 2015 prices, but the department's December 2019 estimates pointed to a potential hike of 17% to 58%.

A May 6 Parliament commitee report asserts that while knowing of “the scale of the project’s cost and schedule overruns as early as October 2018,”  the department and officials of project company HS2 Ltd. failed to reveal this information during parliamentary hearings at that time and in May 2019 “even when asked specific questions about the ... delivery timeline and budget.”

In its  annual report for the year ending  March 31, 2019, HS2 Ltd.  “similarly  failed to  give  an accurate  account" of program problems.

“There is no excuse for hiding the nature and extent of the problems the project was facing from Parliament and the taxpayer.”  said Meg Hiller, chair of the House of Commons' public accounts committee, who is a member of the opposition Labour Party.

The findings are among “the most critical, in both the transparency of government and the handling of a project, that I have seen in my nine years in total on the committee,” adds Geoffrey Clifton-Brown, deputy commitee chair, who is a senior member of the governing Conservative Party and a professional chartered surveyor.

The government “has been clear that this project must go forward with a new approach to parliamentary reporting, with clear transparency, strengthened accountability to ministers, and tight control of costs,” says a department spokesman, adding that it has "comprehensively reset" the HS2 program, introducing a revised budget and funding plan, "with significant reforms to ensure the project is delivered in a more disciplined and transparent manner."