WASHINGTON, Jan 10 (Reuters) - The U.S. Treasury has no plans to delay the 2021 income tax filing season past the normal April 18 deadline after giving taxpayers more time to file returns during each of the two previous years due to the COVID-19 pandemic, Treasury officials said on Monday. The Internal Revenue Service will begin accepting individual income tax returns on Jan. 24, the official said. This is three weeks earlier than last year, when the filing deadline was ultimately delayed until May 17. In 2020, the first year of the pandemic when lockdowns were widespread, the tax filing deadline was delayed to July 15, which contributed to an increased backlog of unprocessed returns. Treasury officials said the backlog, typically around 1 million returns, has grown to several million, largely due to COVID-19 related challenges, including fewer available personnel to process returns. The Treasury said, however, that most taxpayers should still be able to receive direct-deposit refunds within 21 days of filing electronically, barring any issues with processing of their returns. The Treasury is seeking to make long-term investments of $80 billion over a decade into the IRS, including customer service personnel, new data-processing systems and the ability to audit more complex returns as part of the Biden Administration"s Build Back Better legislation. But the Democrats" $1.75 trillion social and climate spending package faces an uncertain future in Congress due to opposition from some moderate lawmakers in the party to certain provisions.