Insolvency is the inability of a debtor to pay their debt.Cash flow insolvency involves a lack of liquidity to pay debts as they fall due. Balance sheet insolvency involves having negative net assets—where liabilities exceed assets. Insolvency is not a synonym for bankruptcy, which is a determination of insolvency made by a court of law with resulting legal orders intended to resolve the insolvency.

A business may be cash-flow insolvent but balance-sheet solvent if it holds illiquid assets, particularly against short term debt that it cannot immediately realize if called upon to do so. Conversely, a business can have negative net assets showing on its balance sheet but still be cash-flow solvent if ongoing revenue is able to meet debt obligations, and thus avoid default: for instance, if it holds long term debt. Many large companies operate permanently in this state.

Insolvency is defined both in terms of cash flow and in terms of balance sheet in the UK Insolvency Act 1986, Section 123, which reads in part:

John Cullen (born August 2, 1964) is a Canadian former professional ice hockey centre who played in the National Hockey League (NHL) for the Pittsburgh Penguins, Hartford Whalers, Toronto Maple Leafs and Tampa Bay Lightning. He was a standout player for Boston University and is the school's all-time leading scorer. After the Buffalo Sabres selected him in the 1986 NHL Supplemental Draft but chose not to offer him a contract, Cullen signed with the Flint Spirits of the International Hockey League (IHL) for the 1987–88 season where he was named the IHL's co-Rookie of the Year and Most Valuable Player after leading the league in scoring.

His career was halted in 1997 when he was diagnosed with Non-Hodgkin lymphoma. He attempted a brief comeback in 1998 after an 18-month battle with the disease, for which the NHL awarded him the Bill Masterton Memorial Trophy, before retiring to serve as an assistant coach for a year with the Lightning. Cullen played in two NHL All-Star Games in his career. He joined his brother in the car dealership business after leaving the game, and briefly operated his own dealership until forced to close during the automotive industry crisis of 2008–2010.