The filing season open follows IRS work to update its programming and test its systems to factor in the second Economic Impact Payments and other tax law changes. These changes are complex and take time to help ensure proper processing of tax returns and refunds as well as coordination with tax software industry, resulting in the February 12 start date.
The IRS must ensure systems are prepared to properly process and check tax returns to verify the proper amount of EIP's are credited on taxpayer accounts – and provide remaining funds to eligible taxpayers.
Although tax seasons frequently begin in late January, there have been five instances since 2007 when filing seasons did not start for some taxpayers until February due to tax law changes made just before the start of tax time.
Source: irs.gov