Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 02, 2023	Apr. 03, 2022	Apr. 02, 2023	Apr. 03, 2022
Revenue	$ 1,158,226	$ 852,744	$ 2,052,991	$ 1,711,255
Gross profit	170,846	135,173	324,091	274,940
Selling, general and administrative expenses	(82,347)	(60,480)	(138,848)	(113,001)
Acquisition and integration expenses	(19,944)	0	(23,705)	0
Contingent consideration – fair value adjustments	(7,544)	(173)	(8,477)	(199)
Income from operations	61,011	74,520	153,061	161,740
Interest expense, net	(13,323)	(3,144)	(18,695)	(6,048)
Other non-operating income	21,407	0	89,402	0
Income before income tax expense	69,095	71,376	223,768	155,692
Income tax expense	(26,254)	(18,327)	(64,212)	(34,144)
Net income	42,841	53,049	159,556	121,548
Net income attributable to noncontrolling interests	(11)	(9)	(20)	(19)
Net income attributable to Tetra Tech, basic	42,830	53,040	159,536	121,529
Net income attributable to Tetra Tech, diluted	$ 42,830	$ 53,040	$ 159,536	$ 121,529
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 0.80	$ 0.99	$ 3.00	$ 2.25
Diluted (in dollars per share)	$ 0.80	$ 0.98	$ 2.98	$ 2.23
Weighted-average common shares outstanding:
Basic (in shares)	53,227	53,834	53,165	53,916
Diluted (in shares)	53,627	54,346	53,595	54,492
Subcontractor costs
Cost of revenue	$ (188,661)	$ (153,103)	$ (346,865)	$ (332,280)
Other costs of revenue
Cost of revenue	$ (798,719)	$ (564,468)	$ (1,382,035)	$ (1,104,035)