The following table summarizes the aggregate workers' compensation reserve activity (in thousands):


	Years Ended December 31,
	2022			2021			2020
Beginning balance
Workers' compensation claims liabilities	$	279,407		$	357,746		$	438,986
Add: claims expense accrual
Current period		19,146			75,786			147,097
Prior periods		(11,337	)		(9,225	)		(6,383	)
		7,809			66,561			140,714
Less: claim payments related to
Current period		4,450			15,063			22,877
Prior periods		67,581			129,138			198,620
		72,031			144,201			221,497
Change in claims incurred in excess of retention limits		802			(699	)		(457	)
Ending balance
Workers' compensation claims liabilities	$	215,987		$	279,407		$	357,746
Incurred but not reported (IBNR)	$	110,824		$	153,838		$	210,798

Ratio of IBNR to workers' compensation claims liabilities		51	%		55	%		59	%

The Company provides workers’ compensation coverage for client employees primarily through arrangements with fully licensed, third-party insurers (the “insured program”). Under this program, carriers issue policies or afford coverage to the Company’s clients under a program maintained by the Company. Approximately 83% of the Company’s workers’ compensation exposure is covered through the insured program.

The Company entered into a new arrangement for its insured program effective July 1, 2021 whereby third-party insurers assumed all risk of loss for claims incurred from July 1, 2021 to June 30, 2022 (the “2021-2022 Policy”). The 2021-2022 Policy allows for premium adjustments depending on overall policy performance. If claims develop favorably, BBSI can participate in the savings up to $20.0 million for the twelve-month policy period. If claims develop adversely, additional premium may be charged up to $7.5 million for the twelve-month policy period.

Effective July 1, 2022, the Company renewed the arrangement for its insured program, which now continues through June 30, 2023 (the “2022-2023 Policy”). Under the renewed arrangement, the Company can participate in savings up to $22.5 million for the twelve-month policy period. For the 2022-2023 Policy, no additional premium may be charged if claims develop adversely. The 2022-2023 Policy includes a renewal commitment through June 30, 2024.

For claims incurred under the insured program prior to July 1, 2021, the Company retains risk of loss up to the first $3.0 million per occurrence on policies issued after June 30, 2020 and $5.0 million per occurrence on policies issued before that date.

On June 29, 2020, the Company entered into a loss portfolio transfer agreement (“LPT 1”) to remove all outstanding workers’ compensation claims obligations for claims incurred under its insured program between February 1, 2014 and December 31, 2017. This transaction reduced the Company’s outstanding workers’ compensation liabilities and trust account balances by $115.7 million.

On June 30, 2021, the Company entered into a loss portfolio transfer agreement (“LPT 2”) to remove all remaining outstanding workers’ compensation claims obligations for client policies issued under its insured program up to June 30, 2018. This transaction reduced the Company’s outstanding workers’ compensation liabilities by $53.1 million.

The Company is required to maintain minimum collateral levels for certain policies issued under the insured program, which is held in a trust account (the “trust account”). The balance in the trust account was $188.2 million and $273.6 million at December 31, 2022 and December 31, 2021, respectively. The trust account balance is included as a component of the current and long-term restricted cash and investments in the Company’s condensed consolidated balance sheets.

The Company is a self-insured employer with respect to workers' compensation coverage for all employees, including employees of PEO clients that elect to participate in our workers’ compensation program, working in Colorado, Maryland and Oregon. In the state of Washington, state law allows only the Company's staffing services and internal management employees to be covered under the Company's self-insured workers' compensation program. The Company also operates a wholly owned, fully licensed insurance company, Ecole, which provides workers’ compensation coverage to client employees working in Arizona and Utah. Approximately 17% of the Company’s workers’ compensation exposure is covered through self-insurance or Ecole (the “self-insured programs”).

For all claims incurred under the Company’s self-insured programs, the Company retains risk of loss up to the first $3.0 million per occurrence, except in Maryland and Colorado, where the Company’s retention per occurrence is $1.0 million and $2.0 million, respectively. For claims incurred under the Company’s self-insured programs prior to July 1, 2020, the Company retains risk of loss up to the first $5.0 million per occurrence, except in Maryland and Colorado, where the retention per occurrence is $1.0 million and $2.0 million, respectively.

The states of California, Maryland, Oregon, Washington, Colorado and Delaware required the Company to maintain collateral totaling $54.5 million and $58.4 million at December 31, 2022 and 2021, respectively, to cover potential workers’ compensation claims losses related to the Company’s current and former status as a self-insured employer. At December 31, 2022, the Company provided surety bonds totaling $54.5 million, including a California requirement of $22.3 million.

The Company provided a total of $216.0 million and $279.4 million at December 31, 2022 and 2021, respectively, as an estimated future liability for unsettled workers' compensation claims liabilities. Of this amount, $3.0 million and $2.2 million on December 31, 2022 and 2021, respectively, represent case reserves incurred in excess of the Company’s retention. The accrual for costs incurred in excess of retention limits is offset by a receivable from insurance carriers of $3.0 million and $2.2 million at December 31, 2022 and 2021, respectively, included in other assets in the consolidated balance sheets.