Income Taxes	3 Months Ended
Income Taxes	Jan. 02, 2021
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income tax expense includes a provision for federal, state and foreign taxes based on the annual estimated effective tax rate applicable to us and our subsidiaries, adjusted for items which are considered discrete to the period. Our effective tax rate on income before income taxes for the three months ended January 2, 2021 of 99.0% was higher than the U.S. federal tax rate of 21.0% primarily due to the establishment of valuation allowances for certain foreign deferred tax assets, the impact of income subject to foreign tax rates that are higher than the U.S. tax rates, the deferred taxes on foreign earnings not considered permanently reinvested, stock-based compensation not deductible for tax purposes and limitations on the deductibility of compensation under Internal Revenue Code Section 162(m). These amounts are partially offset by the benefit of federal research and development tax credits and our Singapore tax exemption. We assess our ability to realize our net deferred tax assets on a quarterly basis and establish a valuation allowance if it is more-likely-than-not that some portion of the deferred tax assets will not be realized. Although several factors may be considered for assessing the need for a valuation allowance, a 12-quarter cumulative loss is generally viewed as a primary factor based on the weight given to historical results versus projections. In Germany we have an "Organschaft" arrangement among our German entities in which the annual profit and loss results are ultimately pooled at the parent level of Coherent Holding B.V. & Co. KG. During the first quarter of fiscal 2021, our German pooled results reflected a loss and we now have a cumulative loss position for the last 12 quarters. Due to the weight of objectively verifiable negative evidence, we believe that it is now more likely-than-not that our German Organschaft group’s deferred tax assets will not be realized as of first quarter of fiscal 2021. Accordingly, we have recorded a valuation allowance of approximately $7.0 million related to these deferred tax assets. It is reasonably possible that significant positive evidence may become available to reach a conclusion that a significant portion of the valuation allowance will no longer be needed, and if so, we may release our valuation allowance in the future. Our effective tax rate on income before income taxes for the three months ended December 28, 2019 of 23.3% was higher than the U.S. federal tax rate of 21.0% primarily due to the impact of income subject to foreign tax rates that are higher than the U.S. tax rates, an accrual for foreign withholding taxes on certain current year foreign earnings not considered permanently reinvested, stock-based compensation not deductible for tax purposes and limitations on the deductibility of compensation under Internal Revenue Code Section 162(m). These amounts are partially offset by the net excess tax benefits from restricted stock unit vesting, the benefit of federal research and development tax credits, the benefit of certain tax audit settlements and our Singapore tax exemption.

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.