loan losses and the allowance for off-balance sheet credit exposures, which is accounted for as a separate liability in other liabilities on the balance sheet. The level of the allowance represents management’s estimate of expected credit losses over the expected life of the loans at the balance sheet date.
Upon adoption of ASC 326 or CECL on January 1, 2021, the Company replaced the incurred loss impairment model that recognizes losses when it became probable that a credit loss will be incurred, with a requirement to recognize lifetime expected credit losses immediately when a financial asset is originated or purchased. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of loans to present the net amount expected to be collected on the loans. Loans, or portions thereof, are charged off against the allowance when they are deemed uncollectible. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged- off. The allowance is comprised of reserves measured on a collective (pool) basis based on a lifetime loss-rate model when similar risk characteristics exist. Loans that do not share risk characteristics are evaluated on an individual basis, generally larger non-accruing commercial loans and TDRs.
The Company uses the discounted cash flow (DCF) method to estimate expected credit losses for all loan portfolio segments measured on a collective (pool) basis. For each loan segment, the Company generates cash flow projections at the instrument level wherein payment expectations are adjusted for estimated prepayment speeds, probability of default, and loss given default. The modeling of prepayment speeds is based on historical internal data.
The Company uses regression analysis of historical internal and peer data to determine suitable loss drivers to utilize when modeling lifetime probability of default. This analysis also determines how expected probability of default and loss given default will react to forecasted levels of the loss drivers. For all loan pools utilizing the DCF method, management utilizes various economic indicators such as changes in unemployment rates, gross domestic product, property values, housing starts, and other relevant factors as loss drivers. For all DCF models, management has determined that due to historic volatility in economic data, two quarters currently represents a reasonable and supportable forecast period, followed by a six-period reversion to historical mean levels for each of the various economic indicators.
The combination of adjustments for credit expectations (default and loss) and timing expectations (prepayment, curtailment, and time to recovery) produces an expected cash flow stream at the instrument level. Specific instrument effective yields are calculated, net of the impacts of prepayment assumptions, and the instrument expected cash flows are then discounted at that effective yield to produce an instrument-level Net Present Value (NPV). An allowance is established for the difference between the instrument’s NPV and amortized cost basis.
The allowance evaluation also considers various qualitative factors, such as: (i) changes to lending policies, underwriting standards and/or management personnel performing such functions, (ii) delinquency and other credit quality trends, (iii) credit risk concentrations, if any, (iv) changes to the nature of the Company's business impacting the loan portfolio, (v) and other external factors, that may include, but are not limited to, results of internal loan reviews, stress testing, examinations by bank regulatory agencies, or other events such as a natural disaster.
Arriving at an appropriate level of allowance involves a high degree of judgment. The determination of the adequacy of the allowance and provisioning for estimated losses is evaluated regularly based on review of loans, with particular emphasis on non-performing and other loans that management believes warrant special consideration. While management uses available information to recognize losses on loans, changing economic conditions and the economic prospects of the borrowers may necessitate future additions or reductions to the allowance.
Individually Evaluated Loans: Prior to the adoption of CECL on January 1, 2021, a loan was individually evaluated when the loan was considered impaired. Impaired loans were based on current information and events, it is probable that the Company will not be able to collect all amounts due from the borrower in accordance with the contractual terms of the loan, including scheduled interest payments.
With the adoption of CECL, loans that do not share risk characteristics with existing pools are evaluated on an individual basis. For loans that are individually evaluated and collateral dependent, financial loans where the Company has determined that foreclosure of the collateral is probable, or where the borrower is experiencing financial difficulty and the Company expects repayment of the financial asset to be provided substantially through the operation or sale of the collateral, the ACL is measured