Financial Due Diligence Red Flags — Complete Checklist
Published February 2026
Red flags don't mean walk away — they mean dig deeper. The most expensive acquisitions are the ones where red flags were missed, not the ones where they were found.
70%+
Of deals have material adjustments
3–5×
Valuation impact of missed red flags
Early
Best time to catch them
Overview
During QoE analysis, red flags are early warning signals that warrant deeper investigation. They range from minor classification issues to deal-breaking findings. This checklist covers the most common red flags organized by financial statement area.
Revenue Red Flags
Revenue hockey stick
Dramatic revenue increase in the most recent period — often coincides with the decision to sell
Customer concentration > 20%
Single customer representing more than 20% of revenue creates significant key-customer risk
Declining recurring revenue
Subscription or contract revenue declining while total revenue grows — sustainability concern
Revenue/AR disconnect
Revenue growing but AR growing faster — signals collection issues or aggressive recognition
Unusual period-end revenue
Revenue spikes in the last week of each period suggest timing manipulation
Related-party revenue
Revenue from entities controlled by the seller may not continue post-acquisition
Expense Red Flags
Declining maintenance spend
Deferred maintenance inflates near-term earnings but creates future capital requirements
Missing expenses
Key cost categories (insurance, legal, accounting) with unusually low or zero balances
Gross margin expansion
Margins improving without clear operational explanation — may indicate cost deferral
Owner comp well above market
Signals potential add-back, but verify it's not compensating for underpaid staff
Expense reclassification
Operating expenses moved below the line to inflate operating income
Excessive add-backs
Total adjustments exceeding 30-40% of reported EBITDA warrant heavy scrutiny
Balance Sheet Red Flags
Inventory build-up
Inventory growing faster than revenue — potential obsolescence or overstatement
Aging AR deterioration
Increasing percentage of AR in 60+ day buckets signals collection problems
Unrecorded liabilities
Pending litigation, warranty obligations, or tax exposures not on the balance sheet
Goodwill or intangibles
Large intangible assets may indicate prior acquisitions with integration risk
Related-party receivables
Loans to owners or related entities that may not be collectible
Inadequate reserves
Bad debt, warranty, or inventory reserves below historical loss rates
Cash Flow Red Flags
Earnings/cash divergence
Net income positive but operating cash flow negative — a classic manipulation signal
Commingled personal funds
Personal and business bank accounts intermingled — makes validation nearly impossible
Unexplained cash movements
Large transfers without clear business purpose
GL-to-bank discrepancies
Cash per the books doesn't match cash at the bank — see proof of cash
For detailed methodology, see our cash and bank tie-out guide.
GL-Level Red Flags
Round-dollar journal entries
Large round amounts suggest estimates or manual overrides
Period-end entry clustering
Many journal entries in the last days of the quarter — potential window dressing
Entries without descriptions
Journal entries lacking adequate explanation may be concealing their purpose
Duplicate payments
Same vendor, same amount, close dates — indicates weak controls or potential fraud
Deep dive: General Ledger Review guide.
Operational Red Flags
Key employee dependency
Critical operations depending on 1-2 individuals who may leave post-acquisition
Customer churn acceleration
Customer loss rate increasing — revenue sustainability risk
Supplier concentration
Single-source suppliers create supply chain vulnerability
Pending regulatory changes
New regulations that could materially increase compliance costs
Litigation exposure
Active or threatened lawsuits with material potential liability
Contract expirations
Key contracts (leases, customer agreements) expiring near or after close