The total cost of the programme is also affected by the timing of funding. Up to 2022-23, HS2 Ltd had some flexibility to move funding between financial years and secured the level of annual funding it requested from DfT to meet the planned schedule. However, in March 2023, DfT instructed HS2 Ltd to meet an annual funding constraint for 2023-24 and 2024-25, in response to HM Treasury spending restraints for those years aimed at managing inflationary pressures. To meet its annual budget, HS2 Ltd slowed work on Phase 2a, Euston and parts of Phase 1, including pausing the start of major construction work on Phase 2a for two years. In March 2024, HS2 Ltd assessed that this deferral would increase Phase 1 costs by between £1.9 billion and £3.1 billion (2019 prices). These deferral costs have not yet been assured and approved by DfT.