Company: ISBA
Filing Date: 2025-03-12
Form Type: 10-K
Source: 0000842517-25-000053
Chunk: 66

Company: ISABELLA BANK CORP
Filing Date: 2025-03-12
Form: 10-K
Item: Item 8
Chunk 66
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 calculated as the product of PD (adjusted for attrition), LGD, and EAD. PD and PA were estimated by analyzing internally sourced data related to historical performance of each loan pool over an economic cycle. PD and PA were adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over a reasonable and supportable forecast period. After the reasonable and supportable forecast period, the forecasted macroeconomic variables were reverted to their historical mean utilizing a rational, systematic basis. The LGD was based on historical recovery averages for each loan pool, adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over the reasonable and supportable forecast period. EAD was estimated using a linear regression model that estimates the average percentage of the loan balance that remains at the time of default. In some cases, management determined that an individual loan exhibited unique risk characteristics which differentiated the loan from other loans with the identified loan pools. In such cases the loans were evaluated for expected credit losses on an individual basis and excluded from the collective evaluation. Management qualitatively adjusted model results for risk factors that were not considered within the modeling processes but were nonetheless relevant in assessing the expected credit losses within the loan pools. These qualitative factor adjustments modified management’s estimate of expected credit losses by a calculated percentage or amount based upon the estimated level of risk.

Auditing management’s estimate of the ACL involved a high degree of subjectivity due to the nature of the qualitative factor adjustments included in the allowances for credit losses and complexity due to the implementation of the PD, PA, LGD, and EAD models (the “Models”). Management’s identification and measurement of the qualitative factor adjustments is highly judgmental and could have a significant effect on the ACL.

How We Addressed the Matter in Our Integrated Audit

We obtained an understanding of the Corporation’s process for establishing the ACL, including the implementation of Models and the qualitative factor adjustments of the ACL. We evaluated the design and tested the operating effectiveness of related controls over the reliability and accuracy of data used to calculate and estimate the various components of the ACL, the accuracy of the calculation of the ACL, management’s review and approval of methodologies used to establish the ACL, validation procedures over the Models, analysis of changes in various components of the ACL relative to changes in the Corporation’s loan portfolio and economy and evaluation of the overall reasonableness and appropriateness of the ACL. In doing so, we tested the operating effectiveness of review and approval controls in the Corporation’s governance process designed to identify and assess