On a consolidated basis, activity in benefits payable was as follows for the three months ended March 31, 2022 and 2021:


	For the three months ended March 31,
	2022		2021
	(in millions)
Balances, beginning of period	$	8,289	$	8,143



Acquisitions	—		42
Incurred related to:
Current year	19,985		17,851
Prior years	(360)		(555)
Total incurred	19,625		17,296
Paid related to:
Current year	(12,284)		(10,842)
Prior years	(6,252)		(5,988)
Total paid	(18,536)		(16,830)


Balances, end of period	$	9,378	$	8,651

Amounts incurred related to prior periods vary from previously estimated liabilities as the claims ultimately are settled. Negative amounts reported for incurred related to prior years result from claims being ultimately settled for amounts less than originally estimated (favorable development).

Our reserving practice is to consistently recognize the actuarial best estimate of our ultimate liability for claims. Actuarial standards require the use of assumptions based on moderately adverse experience, which generally results in favorable reserve development, or reserves that are considered redundant.

The following discussion provides information about incurred and paid claims development for our Retail and Group and Specialty segments as of March 31, 2022 and 2021, net of reinsurance, and the total estimate of benefits payable for claims incurred but not reported, or IBNR, included within the net incurred claims amounts.

Activity in benefits payable for our Retail segment was as follows for the three months ended March 31, 2022 and 2021:


	For the three months ended March 31,
	2022		2021
	(in millions)
Balances, beginning of period	$	7,675	$	7,428



Acquisitions	—		42
Incurred related to:
Current year	19,078		16,762
Prior years	(328)		(463)
Total incurred	18,750		16,299
Paid related to:
Current year	(11,882)		(10,330)
Prior years	(5,741)		(5,401)
Total paid	(17,623)		(15,731)


Balances, end of period	$	8,802	$	8,038

At March 31, 2022, benefits payable for our Retail segment included IBNR of approximately $5.3 billion, primarily associated with claims incurred in 2022.

Activity in benefits payable for our Group and Specialty segment was as follows for the three months ended March 31, 2022 and 2021:


	For the three months ended March 31,
	2022		2021
	(in millions)
Balances, beginning of period	$	614	$	715




Incurred related to:
Current year	1,078		1,237
Prior years	(32)		(92)
Total incurred	1,046		1,145
Paid related to:
Current year	(573)		(660)
Prior years	(511)		(587)
Total paid	(1,084)		(1,247)


Balances, end of period	$	576	$	613

At March 31, 2022, benefits payable for our Group and Specialty segment included IBNR of approximately $492 million, primarily associated with claims incurred in 2022.