Oregon small businesses face real financial consequences when payroll taxes, Corporate Activity Tax filings, estimated payments, and bookkeeping are handled incorrectly. Oregon’s CAT applies to gross receipts above $1 million annually – not net profit – meaning businesses can owe tax even in unprofitable years. Payroll penalties compound at 5% per month. Estimated tax underpayments accrue daily interest, though the safe harbor rule eliminates this penalty for those who plan ahead. Worker misclassification carries back-tax liability that can span multiple years. Clean, reconciled bookkeeping is the foundation for avoiding all of these issues. Oregon business owners in 2026 need to understand registration thresholds, quarterly deadlines, and accurate categorization before year-end pressure hits.