Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 02, 2023	Jul. 03, 2022	Jul. 02, 2023	Jul. 03, 2022
Revenue	$ 1,208,947	$ 890,231	$ 3,261,938	$ 2,601,485
Gross profit	188,846	144,584	512,937	419,524
Selling, general and administrative expenses	(89,064)	(60,942)	(227,912)	(173,943)
Acquisition and integration expenses	(2,107)	0	(25,812)	0
Contingent consideration – fair value adjustments	0	263	(8,477)	64
Income from operations	97,675	83,905	250,736	245,645
Interest expense, net	(14,869)	(2,919)	(33,563)	(8,967)
Other non-operating income	0	0	89,402	0
Income before income tax expense	82,806	80,986	306,575	236,678
Income tax expense	(22,568)	(22,329)	(86,781)	(56,473)
Net income	60,238	58,657	219,794	180,205
Net income attributable to noncontrolling interests	(3)	(7)	(23)	(26)
Net income attributable to Tetra Tech, basic	60,235	58,650	219,771	180,179
Net income attributable to Tetra Tech, diluted	$ 60,235	$ 58,650	$ 219,771	$ 180,179
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 1.13	$ 1.10	$ 4.13	$ 3.35
Diluted (in dollars per share)	$ 1.12	$ 1.09	$ 4.10	$ 3.32
Weighted-average common shares outstanding:
Basic (in shares)	53,231	53,507	53,188	53,777
Diluted (in shares)	53,653	54,006	53,615	54,328
Subcontractor costs
Cost of revenue	$ (221,387)	$ (169,745)	$ (568,252)	$ (502,024)
Other costs of revenue
Cost of revenue	$ (798,714)	$ (575,902)	$ (2,180,749)	$ (1,679,937)