Abstract: The late and insufficient formation of provisions for credit losses became one of the causes of the global financial crisis of 2008-2009. In response to the challenges posed to the international community by this crisis, the Basel Committee on Banking Supervision developed Basel III requirements for financial institutions, which include including issues of credit risk assessment. The International Financial Reporting Standards Board has completely revised its vision of credit risk assessment approaches and issued a new standard, IFRS 9 Financial Instruments. However, Basel III and IFRS 9 form only a general framework for the estimation of expected credit losses, leaving a wide field for the application of professional judgment to the estimation of expected credit losses in conditions of financial instability. This creates the risk of manipulation of banks’ financial indicators. The purpose of the work is to conduct a study of Basel III and IFRS 9 «Financial Instruments» approaches to estimating expected credit losses and their application during financial instability caused by various causes. Credit losses are the difference between all the contractual cash flows that the entity is due to receive under the contract and all the cash flows that the entity expects to receive, discounted at the original effective rate of the instrument (or the effective rate adjusted for the credit risk, for instruments in default). The article examines strategies for credit risk management and credit loss minimization, among which the formation of a reserve for expected credit losses has a special place, which has a direct impact on the bank’s financial result and by its nature is the recognition of potential future losses in the current period, which arose on the basis of the past or current event. The article presents a formula for calculating expected credit losses, which allows the bank to assess credit risk not only on the balance sheet, but also on the off-balance sheet part of contractual relations. The methods used to estimate the probability of a counterparty’s default are considered. With the full-scale invasion of russia into Ukraine in 2022, the risk of default of economic entities operating on the territory of Ukraine has increased significantly. Accordingly, expenses for the formation of reserves for expected credit losses increased. The stability of the financial sector is one of the key issues of the wartime economy. Therefore, the article examines the approaches of such banks of Ukraine as JSC CB PrivatBank, JSC State Export-Import Bank of Ukraine, JSC Raiffeisen Bank to the assessment of expected credit losses in a period of high uncertainty and the development of strategies for managing the existing credit risk, which is strategically important for Ukraine. Analysis of Ukrainian banks’ ability to overcome the impact of financial instability caused by russia’s full-scale war against Ukraine through the application of professional judgment to estimate expected credit losses in 2022.