Tax revenue in fiscal 2013 will shrink by an estimated 80 billion baht under the government's policy of reducing corporate income tax, says the Revenue Department.
The tax, which stood at 30% for decades, was reduced to 23% in July and will be further cut to 20% on Jan 1.
Taxpayers are allowed to submit corporate income tax submissions twice a year - June 30 and Dec 30.
They must file tax payment applications 150 days from the two cut-off dates.
It is projected that the two tax cuts will reduce revenue by 80 billion baht in fiscal 2013, with an additional loss of revenue of 30 billion baht in fiscal 2014.
To offset shrinking revenue, the Finance Ministry plans to improve the efficiency of the tax-collecting system, saying it will not increase tax rates on other items.
Satit Rungkasiri, director-general of the Revenue Department, said the ministry recently approved a budget of 2 billion baht for upgrading information technology for the tax payment system, especially for collecting value-added tax.
It also plans to create an incentive programme to encourage taxpayers to comply with legal requirements.
For fiscal 2012 ending Sept 30, the Revenue Department reported tax revenue of 1.62 trillion baht, which was 0.5% lower than the target.
The shortfall was due mainly to corporate income tax revenue of 544 billion baht being 9.2% down from the target of 599 billion baht.