Interim Budget 2019: Why outgoing govts don't present full-fledged Budgets

What is an interim Budget? What prevents an outgoing government from presenting a full-fledged Budget?

As the financial year in India ends on March 31, no money can be spent after that from government coffers without obtaining parliamentary approval. Thus governments of the day present an interim Budget, which is essentially a stop-gap arrangement, that ensures that it has the necessary funds to spend so that the working of the government does not come to a standstill once the financial year ends. The interim Budget is followed up by a full Budget that is presented by the new government that