Acquisitions and Divestitures (Tables)

12 Months Ended

Sep. 28, 2025

Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]

Summary of preliminary purchase price allocation

The table below represents the purchase price allocation for RPS based on estimates, assumptions, valuations and other analyses as of January 23, 2023. The all cash purchase consideration, excluding the aforementioned forward contract gain, was allocated to the tangible and intangible assets, and liabilities of RPS based on their estimated fair values, with any excess purchase consideration allocated to goodwill as follows (in thousands):

	Amount
Cash and cash equivalents	$	32,093
Accounts receivable and contract assets	202,303
Prepaid expenses and other current assets	45,999
Income taxes receivables	1,999
Property and equipment	38,435
Right-of-use assets, operating leases	40,179
Intangible assets	174,094
Deferred income taxes	35,084
Other long-term assets	1,061
Total assets acquired	571,247
Account payable	$	(44,376)
Accrued compensation	(19,073)
Contract liabilities	(46,287)
Income tax payable	(7,083)
Short-term lease liabilities, operating leases	(13,477)
Other current liabilities	(135,474)
Current portion of long-term debt	(91,973)
Long-term lease liabilities, operating leases	(26,702)
Other long-term liabilities	(13,742)
Deferred tax liabilities	(41,613)
Total liabilities assumed	(439,800)
Fair value of net assets acquired	131,447
Goodwill	652,762
Total purchase consideration	$	784,209

Summary of fair value assigned to acquired intangible assets

The following table summarizes the estimated fair values that were assigned to intangible assets at the acquisition date:

	Fair Value		Weighted-Average Estimated Useful Life
	(in thousands)		(in years)
Backlog	$	27,880	1.6
Trade names	27,260		3.0
Client relations	118,954		11.1
Total intangible assets acquired	$	174,094	8.3

Summary of supplemental consolidated financial results

Following are the supplemental consolidated financial results of Tetra Tech and RPS on an unaudited pro forma basis, as if the RPS acquisition had been consummated as of the beginning of fiscal 2023 (in thousands):

	Fiscal Year Ended
	October 1, 2023
Revenue	$	4,780,404
Net income including noncontrolling interests	223,857

Summary of estimated contingent earn out liabilities

The following table summarizes the changes in the fair value of estimated contingent consideration (in thousands):

	Fiscal Year Ended
	September 28, 2025		September 29, 2024		October 1, 2023
Beginning balance	$	48,746	$	73,422	$	65,566
Estimated earn-out liabilities for acquisitions	43,493		23,038		12,248
Payments of contingent consideration	(26,225)		(54,050)		(21,328)
Adjustments to fair value reported in earnings	(12,228)		2,541		12,255
Interest accretion expense	2,661		2,639		2,480
Effect of foreign currency exchange rate changes	514		1,156		2,201
Ending balance	$	56,961	$	48,746	$	73,422
Maximum potential payout at end of period	$	120,182	$	102,006	$	113,820