While Sitharaman has so far resisted calls for any significant fiscal stimulus to revive the economy, bond traders fear the weak economic print last Friday may force the government to give in. Speculation it may then push up its planned borrowing from a record Rs 7.1 trillion helped benchmark sovereign notes cap their worst performance in 16 months in August.
Sitharaman has said she hasn't decided yet on how the RBI funds will be used. The cash is more than enough to pay income support to farmers and recapitalise troubled state banks this year.
Countries traditionally fund their large expenditure programmes from taxes. India's tax collection in the four months through July was only a fifth of the budget target of Rs 16.5 trillion. The shortfall last year forced the government to slash expenditure to meet the fiscal gap goal.
The country's tax-to-GDP ratio of about 11% ranks lower than the global average and has fallen despite an amnesty programme in 2016, which was followed by a surprise clampdown on cash to nab tax evaders.
The government is penciling in a 12% increase in collections this year, based on economic expansion of 7%. That may be over-optimistic, given that GDP growth in the June quarter slowed to 5%.
In the run-up to elections earlier this year, Prime Minister Narendra Modi announced a flurry of ambitious programmes to win over voters. Since returning to power with a bigger margin, he now has to find resources to fund recurring expenses for farm income, employment guarantees and health access.
The success of the assets sale programme is also uncertain, given declining investor appetite and volatile financial markets.
The government will need to reduce its dependence on RBI transfers to bridge fiscal gaps and re-look at asset sales and improving tax compliance, said analysts led by Suvodeep Rakshit at Kotak Institutional Equities.