Underwriting is the process of assessing risk before issuing a loan or insurance policy. The underwriter evaluates the applicant's financial situation, the collateral, and the likelihood of default or loss. Based on that assessment, the underwriter decides whether to approve the application and on what terms. It is a gatekeeping function. Bad underwriting leads to losses. Good underwriting balances risk and approval rates.

In lending, underwriting focuses on the borrower's ability and willingness to repay. Lenders review credit history, income, employment, assets, and debts. They calculate the debt-to-income ratio and check the credit score. For mortgages, they order an appraisal to confirm the property's value. For business loans, they review financial statements, tax returns, and business plans. The underwriter may approve, deny, or approve with conditions, like a higher down payment or a co-signer.

In insurance, underwriting focuses on the likelihood of a claim. Auto insurers look at driving record, age, location, and vehicle type. Life insurers look at age, health, occupation, and hobbies. Health insurers look at medical history and pre-existing conditions, though the Affordable Care Act limits how they can use that information. The underwriter sets the premium and may exclude certain risks.

Underwriting has become more automated. Algorithms and data analytics now handle much of the work, especially for small loans and standard policies. But complex cases still require human judgment. The best underwriters combine data with experience and a healthy skepticism.