Activity in the liability for unpaid claims, including claims adjustment expenses, for the three months ended March 31, 2021 and 2020, is summarized as follows:


Three Months Ended March 31,	2021		2020
	(in thousands)
Beginning of period balance - gross and net	$	103,976	$	77,886
Incurred related to:
Current year		213,147		146,440
Prior years		1,285		(112	)
Total incurred		214,432		146,328
Paid related to:
Current year		130,459		74,502
Prior years		70,367		59,359
Total paid		200,826		133,861
End of period balance - gross and net	$	117,582	$	90,353

Unpaid claims as of March 31, 2021 were $117.6 million. During the three months ended March 31, 2021, $70.4 million was paid for incurred claims attributable to insured events of prior years. An unfavorable development of $1.3 million was recognized during the three months ended March 31, 2021, resulting from the Corporation's actual experience with claims developing differently as compared to the Corporation's estimates as of December 31, 2020. Original estimates are increased or decreased, as additional information becomes known regarding individual claims. The ratio of current year medical claims paid as a percentage of current year net medical claims incurred was 61.2% for the three months ended March 31, 2021 and 50.9% for three months ended March 31, 2020. This ratio serves as an indicator of claims processing speed, indicating that claims were processed at a faster rate during the three months ended March 31, 2021 than during the three months ended March 31, 2020.

The Corporation uses a variety of standard actuarial techniques to establish unpaid claims reserves. Management estimates are supported by the Corporation's annual actuarial analysis. The Corporation utilizes an actuary to review the adequacy of unpaid claim and unpaid claim adjustment expense. The estimation of claim costs is inherently difficult and requires significant judgement. The estimation has considerable inherent variability and can vary significantly depending upon several factors, including medical cost trends and claim payment patterns, general economic conditions and regulatory changes. The time value of money is not taken into account for the purposes of calculating the liability for unpaid claims. Management believes that the current reserves are adequate based on currently available information.