Over 29 lakh businesses have filed their first tax returns under the Goods and Services Tax (GST) regime before the filing deadline closes today, an official said.The deadline for filing first monthly return under the GST - the new indirect tax regime that unifies over a dozen state and central taxes, including excise duty, service tax and VAT - expired at midnight tonight.

"At the start of the day today, over 29.64 lakh returns had been filed," the official said. "An estimated 15-20 lakh more may file returns by the end of the deadline".

Under the GST, businesses are supposed to file monthly sales returns and pay due taxes online. Since this was the maiden return after GST was rolled out on July 1, the government gave companies extra time to file returns and pay taxes.

GST-Network -- the company managing the tax filing apparatus -- has geared up the IT network to handle the last minute rush to avoid a repeat of last week when the GSTN portal crashed.

As the site crashed on last Saturday, the government postponed the tax filing deadline by five days to August 25.

About 48 lakh taxpayers had saved the sales data on the portal till August 23 and they are just a step away from paying taxes and filing returns. An estimated Rs 50,000 crore had come in from taxes from those returns.

The taxes submitted include Central-GST, State-GST and Integrated-GST as also cess on luxury and demerit goods like cars and tobacco.The collection figure would go up once all the tax payers file returns and pay taxes.

While 72 lakh assessees of the old indirect tax regime have migrated to the GST Network portal, nearly 50 lakh have completed the migration process.

Besides, of the 15 lakh fresh registrations that have happened, as many as 10 lakh are expected to file returns for July