Note 14 - Income Taxes	9 Months Ended
Note 14 - Income Taxes	Sep. 30, 2020
Notes to Financial Statements
Income Tax Disclosure [Text Block]	14. Income Taxes The Company's effective tax rate is approximately 5.8% and 0.7% for the nine -month period ended September 30, 2020 and 2019, respectively. The Company's effective tax rate differs from the statutory federal tax rate of 21% for the nine month period ended September 30, 2020 primarily due to a full valuation allowance recorded on our United States, China and Italy deferred tax assets since we cannot anticipate when or if we will have sufficient taxable income to utilize the deferred tax assets in the future. Further, our effective tax rate differs from the statutory federal tax rate due to state taxes, differences between U.S. and foreign tax rates, foreign losses incurred with no related tax benefit, non-deductible commissions, and non-deductible meals and entertainment expenses for the nine month periods ended September 30, 2020 and 2019. Fuel Tech had no unrecognized tax benefits as of September 30, 2020 and December 31, 2019. On March 27, 2020, President Trump signed into law the Coronavirus Aid, Relief, and Economic Security Act (H.R. 748 ) (the “CARES Act”). Among the changes to the U.S. federal income tax rules, the Cares Act restored net operating loss carryback rules that were eliminated by 2017 Tax Cuts and Jobs Act, restored 100 percent bonus depreciation for qualified improvement property, modified the limit on the deduction for net interest expense and accelerated the timeframe for refunds of AMT credits. At this time we do not anticipate a material impact to the Company's current or deferred income taxes as a result of the CARES Act. We will continue to evaluate the effects of the CARES Act as additional legislative guidance become available.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.