Due diligence encompasses three distinct investigation streams: Commercial Due Diligence (market position and operational viability), Financial Due Diligence (financial statements, cash flow, and revenue analysis), and Legal Due Diligence (contracts, litigation, and intellectual property). Each stream requires specialized expertise and covers different dimensions of the acquisition target. Commercial due diligence examines market trends, competitor analysis, and revenue models. Financial due diligence verifies book records and validates purchase price. Legal due diligence reviews entity documents, contracts, and potential liabilities that could affect the transaction.

Key financial warning signs include artificially inflated revenue through eased customer credit terms before sale, rising churn rates by customer cohort, and spikes in accounts receivable aging. Revenue manipulation tactics involve examining monthly recurring revenue (MRR) and annual recurring revenue (ARR) trends using waterfall analysis. Rising churn by cohort signals deteriorating customer satisfaction or product-market fit. Older accounts receivable becomes harder to collect, with documented seller tactics including loosening credit terms to boost sales numbers pre-sale. Always request 3-5 years of audited and unaudited financial statements for trend analysis.

This forms the first leg of the legal due diligence 'three-legged stool' - confirming valuable assets actually exist and match representations. For intellectual property acquisitions, verify patents, trademarks, copyrights, and trade secrets are properly registered, defensible, and unencumbered. For inventory-based businesses, physically verify inventory exists and matches representations. For customer-based businesses, confirm customer relationships and contracts are transferable. One M&A attorney describes literally climbing silos to verify grain counts during audits. Always check for liens, competing claims, and change-of-ownership opt-out clauses in key agreements.

Tax due diligence covers federal income tax (3 years of returns, pending audits, NOL carryforwards with Section 382 limitations), state income/franchise tax (nexus issues, unfiled returns), and sales tax compliance. Post-Wayfair economic nexus thresholds are low ($100K-$500K in sales), creating liability buyers inherit in stock purchases. Review estimated tax payments, IRS notices, and S-Corp election status. Built-in gains and aggressive tax positions require scrutiny. Tax problems rank as the number one post-closing issue alongside IP disputes, making this review critical for deal pricing and structure.

Request organizational charts showing reporting relationships, governing documents (articles of incorporation, bylaws, amendments), and all material contracts. Key operational items include vendor agreements, customer contracts, employment agreements, and lease documents for buildings and equipment. Verify ERP systems, buy/sell processes, and specialized operational capabilities. Request fleet accounts, fixed asset lists with values, and three years of payroll records. Always examine change-of-ownership clauses that could terminate key relationships upon acquisition. Include insurance coverages detailing both what is and isn't covered.

Follow a natural cadence starting with preliminary due diligence using critical items before signing a Letter of Intent (LOI). After LOI execution, conduct formal due diligence organized into five categories: Critical Items (high-priority preliminary check), Corporate and Legal (entity docs, contracts), Financial (book verification, price validation), Operations (systems and processes), and Sales/Marketing (go-to-market analysis). Each category should be reviewed by specialists with intentional overlaps to capture cross-functional findings. This structured approach prevents ad hoc information gathering and ensures comprehensive coverage.

Understanding seller motivation ranks as a critical strategic rationale item - whether retirement, financial distress, or strategic shift drives the sale. Investigate previous sale attempts and reasons for failure, as this reveals potential deal-killing issues. Prior failed sales often indicate unresolved problems with financials, operations, or legal matters. Document the seller's timeline and urgency, as rushed sales may hide problems. Verify if the business has been shopped to multiple buyers and why previous negotiations failed. This intelligence helps position your offer and identify negotiation leverage points while uncovering potential red flags.

Request actual credit cards, account numbers, and detailed account information for all business credit facilities. Corporate credit reports don't show actual credit card details, making physical verification essential. Examine three years of bank statements and verify relationships with financial institutions. Review all debt agreements, lines of credit, and financial covenants that may be triggered by ownership change. Check for personal guarantees that won't transfer and identify any cross-default provisions. Verify access to all business financial assets and confirm no restrictions on ownership transfer of banking relationships or credit facilities.