Retirement Plans

9 Months Ended

Dec. 24, 2021

Retirement Benefits [Abstract]

Retirement Plans

Retirement PlansThe Company recognizes the funded status (i.e., the difference between the fair value of plan assets and the benefit obligations) of its defined benefit pension plans in its unaudited consolidated balance sheets with a corresponding adjustment to accumulated other comprehensive income, net of tax. These amounts will continue to be recognized as a component of future net periodic benefit costs consistent with the Company’s past practice. Further, actuarial gains and losses and prior service costs that arise in future periods and are not recognized as net periodic benefit costs in the same periods will be

recognized as a component of other comprehensive income. Those amounts will also be recognized as a component of future net periodic benefit costs consistent with the Company’s past practice. The Company uses a measurement date for its defined benefit pension plans and other postretirement benefit plans that is equivalent to its fiscal year-end.

Plan Descriptions

Non-U.S. Defined Benefit Plan

The Company, through its wholly owned subsidiary, Allegro MicroSystems Philippines, Inc. (“AMPI”), has a defined benefit pension plan, which is a noncontributory plan that covers substantially all employees of the respective subsidiary. The plan’s assets are invested in common trust funds, bonds and other debt instruments and stocks.

Effect on the unaudited statements of operations

Expense related to the non-United States (“U.S.”). defined benefit plan was as follows:

	Three-Month Period Ended				Nine-Month Period Ended
	December 24, 2021		December 25, 2020		December 24, 2021		December 25, 2020
Service cost	$	365	$	296	$	1,119	$	843
Interest cost	158		166		485		474
Expected return on plan assets	(75)		(79)		(230)		(231)
Amortization of prior service cost	1		2		1		6
Actuarial loss	51		47		156		126
Net periodic pension expense	$	500	$	432	$	1,531	$	1,218

Information on Plan Assets

The table below sets forth the fair value of the entity’s plan assets as of December 24, 2021 and March 26, 2021, using the same three-level hierarchy of fair value inputs described in the significant accounting policies included in the Company’s 2021 Annual Report.

	Fair Value at December 24, 2021		Level 1		Level 2		Level 3
Assets of non-U.S. defined benefit plan:
Government securities	$	2,005	$	2,005	$	—	$	—
Unit investment trust fund	1,217		—		1,217		—
Loans	578		—		—		578
Bonds	706		—		706		—
Stocks and other investments	2,338		1,224		2		1,112
Total	$	6,844	$	3,229	$	1,925	$	1,690

	Fair Value at March 26, 2021		Level 1		Level 2		Level 3
Assets of non-U.S. defined benefit plan:
Government securities	$	1,646	$	1,646	$	—	$	—
Unit investment trust fund	1,221		—		1,221		—
Loans	584		—		—		584
Bonds	1,112		—		1,112		—
Stocks and other investments	3,081		1,947		1		1,133
Total	$	7,644	$	3,593	$	2,334	$	1,717

The following table shows the change in fair value of Level 3 plan assets for the nine months ended December 24, 2021:

	Level 3 Non-U.S. Defined Plan Assets
	Loans		Stocks
Balance at March 26, 2021	$	584	$	1,133
Additions during the year	308		—
Redemptions during the year	(289)		—
Revaluation of equity securities	(5)		13
Change in foreign currency exchange rates	(20)		(34)
Balance at December 24, 2021	$	578	$	1,112

The investments in the Company’s major benefit plans largely consist of low-cost, broad-market index funds to mitigate risks of concentration within the market sectors. In recent years, the Company’s investment policy has shifted toward a closer matching of the interest-rate sensitivity of the plan assets and liabilities. The appropriate mix of equity and bond investments is determined primarily through the use of detailed asset-liability modeling studies that look to balance the impact of changes in the discount rate against the need to provide asset growth to cover future service cost. The Company, through its wholly owned subsidiary, Allegro MicroSystems, LLC’s (“AML”), non-U.S. defined benefit plan, has added a greater proportion of fixed income securities with return characteristics that are more closely aligned with changes in liabilities caused by discount rate volatility. There are no significant restrictions on the amount or nature of the investments that may be acquired or held by the plans.

During the three- and nine-month periods ended December 24, 2021, the Company contributed approximately $344 and $1,040 to its non-U.S. pension plan, respectively. During the three- and nine-month periods ended December 25, 2020, the Company contributed approximately $249 and $736 to its non-U.S. pension plan, respectively. The Company expects to contribute approximately $1,425 to its non-U.S. pension plan in fiscal year 2022.

Other Defined Benefit Plans

In December 1993, the Company commenced with a rollover pension promise agreement (“Pension Promise”) to offer a then European employee an insured annuity upon their retirement at age 65. The employee was the only eligible participant of the Pension Promise. The impact associated with the expense and related other income with the Pension Promise was insignificant in fiscal years 2021 and 2020, respectively. The total values of the Pension Promise in the amounts of 663 and 928 British Pounds Sterling at December 24, 2021 and March 26, 2021, respectively (approximately $882 and $1,272 at December 24, 2021 and March 26, 2021, respectively), were classified with other in other assets, net and accrued retirement in other long-term liabilities in the Company’s unaudited consolidated balance sheets.

Defined Contribution Plan

The Company has a 401(k) plan that covers all employees meeting certain service and age requirements. Employees are eligible to participate in the plan upon hire when the service and age requirements are met. Employees may contribute up to 35% of their compensation, subject to the maximum contribution allowed by the Internal Revenue Service. All employees are 100% vested in their contributions at the time of plan entry.

Eligible AML U.S. employees may contribute up to 50% of their pretax compensation to a defined contribution plan, subject to certain limitations, and AML may match, at its discretion, 100% of the participants’ pretax contributions, up to a maximum of 5% of their eligible compensation. Matching contributions by AML totaled approximately $655 and $3,000 for the three- and nine-month periods ended December 24, 2021, respectively, and approximately $1,112 and $3,181 for the three- and nine-month periods ended December 25, 2020, respectively.

The Company, through its AML subsidiary, Allegro MicroSystems Europe, Ltd. (“Allegro Europe”), also has a defined contribution plan (the “AME Plan”) covering substantially all employees of Allegro Europe. Contributions to the AME Plan by the Company totaled approximately $209 and $639 for the three- and nine-month periods ended December 24, 2021, respectively, and approximately $207 and $592 for the three- and nine-month periods ended December 25, 2020, respectively.