Income Taxes (Tables)

12 Months Ended

Sep. 30, 2025

Income Tax Disclosure [Abstract]

Summary of Income Before Income Taxes

Our Income before income taxes consisted of the following:

(in thousands)	Year ended September 30,
	2025		2024		2023
Domestic	$	418,265	$	43,504	$	(49,193	)
Foreign		501,912		425,458		381,759
Total income before income taxes	$	920,177	$	468,962	$	332,566

Schedule of Provision For Income Taxes

Our Provision for income taxes consisted of the following:

(in thousands)	Year ended September 30,
	2025			2024			2023
Current:
Federal	$	128,230		$	44,642		$	7,311
State		21,754			25,359			10,020
Foreign		62,479			61,668			53,019
		212,463			131,669			70,350
Deferred:
Federal		(43,333	)		(60,378	)		(11,821	)
State		(15,630	)		(7,387	)		(10,028	)
Foreign		32,680			28,725			38,525
		(26,283	)		(39,040	)		16,676
Provision for income taxes	$	186,180		$	92,629		$	87,026

Summary of Federal Income Tax Rate and Effective Income Tax Rate

Taxes computed at the statutory federal income tax rates are reconciled to the Provision for income taxes as follows:

(in thousands)	Year ended September 30,
	2025					2024					2023
Statutory federal income tax rate	$	193,237		21	%	$	98,482		21	%	$	69,839		21	%
State income taxes, net of federal tax benefit		6,124		1	%		4,631		1	%		577		0	%
Federal research and development credits		(8,552	)	(1	)%		(11,203	)	(2	)%		(7,751	)	(2	)%
Uncertain tax positions		(1,904	)	—			7,268		2	%		23,302		7	%
Foreign tax credit		(14,410	)	(2	)%		(30,119	)	(7	)%		(11,415	)	(3	)%
Foreign rate differences		(12,135	)	(1	)%		(15,368	)	(3	)%		(20,829	)	(6	)%
Foreign tax on U.S. provision		14,452		2	%		15,120		3	%		11,415		3	%
Excess tax benefits from restricted stock		(8,534	)	(1	)%		(9,225	)	(2	)%		(6,963	)	(2	)%
U.S. permanent items		(920	)	—			2,711		0	%		5,341		2	%
Non-deductible compensation		9,096		1	%		10,157		2	%		8,344		3	%
Base Erosion Anti-Abuse Tax (BEAT)		2,653		—			3,264		1	%		—		—
GILTI, net of foreign tax credits		27,008		3	%		31,388		7	%		17,861		5	%
Foreign-Derived Intangible Income (FDII)		(20,162	)	(2	)%		(15,148	)	(3	)%		(8,987	)	(3	)%
Non-deductible imputed interest		—		—			—		—			6,292		2	%
Other, net		227		(1	)%		671		0	%		—		(1	)%
Provision for income taxes	$	186,180		20	%	$	92,629		20	%	$	87,026		26	%

Schedule of Deferred Tax Assets and Liabilities

The significant temporary differences that created deferred tax assets and liabilities are shown below:

(in thousands)	September 30,
	2025			2024
Deferred tax assets:
Net operating loss carryforwards	$	12,074		$	14,141
Foreign tax credits		5,996			2,028
Capitalized research and development		176,610			136,001
Pension benefits		6,868			7,629
Prepaid expenses		22,391			18,551
Deferred revenue		2,970			2,607
Stock-based compensation		23,514			22,231
Other reserves not currently deductible		39,888			34,422
Amortization of intangible assets		36,560			60,527
Research and development and other tax credits		8,984			25,706
Lease liabilities		43,650			46,460
Fixed assets		114,109			106,741
Capital loss carryforward		4,517			3,875
Other		5,608			3,528
Gross deferred tax assets		503,739			484,447
Valuation allowance		(8,529	)		(21,755	)
Total deferred tax assets		495,210			462,692
Deferred tax liabilities:
Acquired intangible assets not deductible		(246,107	)		(257,731	)
Lease assets		(29,298	)		(34,160	)
Pension prepayments		(4,279	)		(3,283	)
Deferred revenue		(10,212	)		(1,243	)
Depreciation		(3,277	)		(4,683	)
Deferred income		(14,518	)		(11,636	)
Prepaid commissions		(14,479	)		(13,738	)
Other		(9,120	)		(9,030	)
Total deferred tax liabilities		(331,290	)		(335,504	)
Net deferred tax assets	$	163,920		$	127,188

Summary of Valuation Allowance

The changes to the valuation allowance were primarily due to the following:

(in thousands)	Year ended September 30,
	2025			2024		2023
Valuation allowance, beginning of year	$	21,755		$	21,695	$	22,283
Net increase (decrease) in deferred tax assets with a full valuation allowance		(13,226	)		60		(588	)
Valuation allowance, end of year	$	8,529		$	21,755	$	21,695

Schedule of Unrecognized Tax Benefit

	Year ended September 30,
Unrecognized tax benefits (in thousands)	2025			2024			2023
Unrecognized tax benefit, beginning of year	$	65,035		$	50,742		$	23,923
Tax positions related to current year:
Additions		14,736			7,570			7,075
Tax positions related to prior years:
Additions		104,375			10,705			20,855
Reductions		(9,669	)		(452	)		—
Settlements		(16,753	)		(3,530	)		—
Statute expirations		—			—			(1,111	)
Unrecognized tax benefit, end of year	$	157,724		$	65,035		$	50,742

Summary of Income Tax Examinations Years

As of September 30, 2025, we remained subject to examination in the following major tax jurisdictions for the tax years indicated:

Major Tax Jurisdiction	Open Years
United States	2022 through 2025
Germany	2019 through 2025
France	2023 through 2025
Japan	2020 through 2025
Ireland	2019 through 2025