After media reports saying that the Modi-government would be presenting a full budget, the provisional calendar released by the Lok Sabha indicated the event on 1 February as Interim Budget.
An interim budget is prepared by governments in democracies when the country will be entering a transitional period. In simple words, the results of the General Assembly elections to be held in May 2019 will decide if whether or not the same political party will remain in power or be voted out. The interim budget is prepared for the transitional time between the end of a financial year till the time that the new government is created and forms its own budget plan. This kind of budget is also known as a vote-on-account budget.

Since the election occurs at the beginning of the first half of the next financial year, it will not be right for the previous government to burden the next government with its budgetary allocations. Additionally, the new government may have a different financial agenda.
Earlier this week, media reports citing government officials said that the BJP government was looking to present a full budget on 1 February.
Amid this speculation, former finance minister Yashwant Sinha said there is no precedence of an outgoing government doing so. "It would be entirely improper and unconstitutional on the part of this government to present a full budget," he said, adding that it should neither table the economy survey, which is generally presented a day before the budget is tabled, not present the Finance Bill.
The budget session is scheduled to begin on January 31.
With inputs from PTI