A loan is impaired when the lender no longer expects to collect everything the borrower promised to pay, meaning some portion of the remaining principal or contractual interest is unlikely to come back. That is the working definition of an impaired loan, and under the accounting rules now in force across U.S. financial institutions, lenders don’t wait for that shortfall to become obvious. They estimate expected credit losses across the entire portfolio from the day each loan is originated, and they carry a reserve against those expected losses on the balance sheet.
The framework driving that approach is the Current Expected Credit Losses (CECL) model, introduced by FASB in ASU 2016-13 and codified as ASC Topic 326. CECL replaced the older “incurred loss” standard, which allowed a loss to be recognized only after it became probable that one had already occurred. The change matters because it pulled loss recognition forward and dissolved the old “probable loss” trigger that used to define impairment as an event. Impairment is now built into the portfolio from origination.1U.S. Department of the Treasury. The Current Expected Credit Loss Accounting Standard and Financial Institution Regulatory Capital Study CECL took effect for large SEC filers in fiscal years beginning after December 15, 2019, and for all other entities in fiscal years beginning after December 15, 2022.2Financial Accounting Standards Board. Credit Losses – Transition By 2026, every U.S. financial institution should be operating under it.
Impairment Is Not the Same as Delinquency
A late payment and an impaired loan are different things. Delinquency is an operational fact about whether a payment arrived on time. Impairment is a judgment about whether the money is ultimately coming back at all.
A borrower who missed last month’s payment but has strong cash flow and solid collateral may not be impaired. A borrower who is current on payments but has just filed for bankruptcy almost certainly is. Financial institutions have to look past the payment ledger and assess long-term capacity to service the debt, the value of any collateral, and the wider economic conditions the borrower operates in.
What Signals a Loan Has Deteriorated
Even under CECL’s portfolio-wide approach, lenders still need to flag loans that have gotten worse than the original loss estimate assumed. The FDIC has acknowledged that this review “requires an institution to consider individual facts and circumstances along with its normal review procedures,” rather than following a single test applied to every loan.3Federal Deposit Insurance Corporation. Questions and Answers on Accounting for Loan and Lease Losses
Some conditions consistently prompt closer review:
- A significant decline in the borrower’s revenue, cash flow, or overall financial condition
- A bankruptcy filing, which signals that contractual repayment is unlikely without restructuring
- A material drop in the value of collateral securing the loan
- Violations of non-payment covenants, such as required financial ratios
- Sector downturns or broader economic shifts that undermine the borrower’s ability to repay
Large, unique loans, such as commercial real estate financing or corporate credit facilities, are typically evaluated individually. Smaller, homogeneous loans like credit card balances, auto loans, and residential mortgages get assessed collectively as pools, using statistical models that reflect historical loss patterns adjusted for current and forecast conditions.
How the Expected Loss Is Measured
CECL gives institutions flexibility. Unlike the old standard, which prescribed three specific measurement methods, CECL allows any approach that produces a reasonable estimate of lifetime expected losses and incorporates past events, current conditions, and reasonable forecasts. Common methods include:
- Discounted cash flow, where projected future cash flows are discounted to present value and the gap against amortized cost is the loss estimate
- Loss-rate methods, which apply historical loss rates to pools of similar loans and adjust for current and expected conditions
- Probability-of-default methods, which combine the likelihood of default with expected loss severity
- Vintage analysis, which tracks and projects losses based on when loans were originated
- Weighted-average remaining maturity, a simpler approach that applies historical loss rates over the average remaining life of a loan pool
Institutions don’t have to pick one method or reconcile their choice against a discounted cash flow calculation. The requirement is a reasonable estimate of expected lifetime losses, not a specific formula.
You’ll still see references to the older three-method framework from FAS 114 (later ASC 310-10-35) in pre-CECL financial statements, textbooks, and regulatory guidance. Those three methods (present value of expected future cash flows, observable market price, and fair value of collateral) no longer govern any U.S. institution that has adopted CECL.
Collateral-Dependent Loans
When repayment depends solely on the underlying collateral, CECL requires the loss estimate to be based on the fair value of that collateral. For regulatory reporting, banks must use this collateral-based measurement for all collateral-dependent loans, regardless of whether foreclosure is probable. If the lender expects to sell the collateral to recover the debt, fair value is reduced by estimated costs to sell; if repayment depends on operating the collateral rather than selling it, no selling-cost adjustment is made. The credit loss is the gap between the loan’s amortized cost and that adjusted collateral value.4Office of the Comptroller of the Currency. Comptroller’s Handbook – Allowances for Credit Losses
Where the Loss Shows Up on the Books
Under CECL, the estimated credit loss feeds an account called the Allowance for Credit Losses (ACL), which replaced the older Allowance for Loan and Lease Losses. The ACL is a contra-asset that reduces the gross loan portfolio to its estimated collectible value.4Office of the Comptroller of the Currency. Comptroller’s Handbook – Allowances for Credit Losses
The mechanics: when the lender increases its loss estimate, it books a credit loss expense on the income statement, which cuts reported earnings for the period, and adds the same amount to the ACL on the balance sheet. If a bank holds a $1 million loan and expects $150,000 in losses, it records $150,000 in credit loss expense and adds $150,000 to the ACL. Net carrying value drops to $850,000.
When a loan is ultimately deemed uncollectible, the institution writes it off by reducing both the gross loan balance and the ACL by the same amount. That write-off doesn’t hit the income statement again because the loss was already recognized through the earlier provision. If some of the written-off amount is later recovered, the recovery is credited back to the ACL.
Nonaccrual Status
Impaired loans often move to nonaccrual status, meaning the bank stops recognizing interest income as it would on a performing loan. Banks are generally required to place a loan on nonaccrual when full payment of principal or interest is not expected, when principal or interest has been in default for 90 days or more (unless the loan is both well secured and in the process of collection), or when the loan is maintained on a cash basis due to the borrower’s deteriorating financial condition.5Office of the Comptroller of the Currency. Bank Accounting Advisory Series 2025
Once a loan is on nonaccrual, cash from the borrower typically reduces principal rather than counting as interest income. The “well secured and in the process of collection” exception is narrow. Simply starting collection efforts, working on a restructuring, or beginning foreclosure doesn’t qualify on its own; timing and amount of repayment must be reasonably certain.5Office of the Comptroller of the Currency. Bank Accounting Advisory Series 2025
Restoring a loan to accrual status takes more than one on-time payment. The borrower needs a sustained period of repayment performance, generally at least six months, and the bank has to be reasonably assured all contractually due amounts will be repaid within a reasonable timeframe.5Office of the Comptroller of the Currency. Bank Accounting Advisory Series 2025
Troubled Debt Restructuring Accounting Is Gone
Under the old rules, a lender that granted concessions to a distressed borrower had to designate the modified loan a Troubled Debt Restructuring (TDR), which carried its own impairment measurement and disclosure regime. In 2022, FASB issued ASU 2022-02, which eliminated TDR accounting entirely for institutions that have adopted CECL.6Federal Reserve System. Saying Goodbye to Troubled Debt Restructurings
Modifications still happen; they just aren’t a separate accounting category anymore. Each modification is evaluated to determine whether it’s a new loan or a continuation of the existing one. It counts as a new loan only when the new terms are at least as favorable to the lender as terms offered to comparable borrowers and the changes are more than minor. ASU 2022-02 replaced the old TDR disclosures with new requirements around modifications to borrowers experiencing financial difficulty, covering the types of concessions granted (rate reductions, principal forgiveness, payment delays, term extensions), how those modified loans performed over the following 12 months, and how the modifications factored into the allowance.6Federal Reserve System. Saying Goodbye to Troubled Debt Restructurings
Tax Treatment Doesn’t Match the Accounting
The GAAP loss and the tax deduction don’t arrive at the same time. Under GAAP, expected losses are booked upfront through the ACL. The IRS allows a bad debt deduction only in the year the debt actually becomes worthless, and the taxpayer must show reasonable steps to collect.7Internal Revenue Service. Topic No. 453, Bad Debt Deduction
Federal tax law splits business bad debts into two categories. If the entire debt becomes worthless during the tax year, the full amount is deductible. When a debt is recoverable only in part, the IRS may allow a deduction for the amount the creditor has charged off during the year, capped at the portion actually written off.8Office of the Law Revision Counsel. 26 USC 166 – Bad Debts For nonbusiness bad debts, the rules are stricter: the debt must be totally worthless before any deduction is available, and partial write-offs aren’t allowed.7Internal Revenue Service. Topic No. 453, Bad Debt Deduction
The persistent gap between the loss shown on GAAP statements (recognized early under CECL) and the deduction available on the tax return (only when the debt is actually charged off or worthless) generates deferred tax assets on a bank’s balance sheet, which regulators watch closely.