The two main approaches to determine whether a company or an individual are insolvent are:
A "cash flow" test, which looks to whether there is sufficient cash (and other realisable assets) available to a company (or a person) to pay creditors as debts fall due for payment.
A "balance sheet" test, which looks to the overall asset position of a company (or a person) and assesses solvency by reference to the value of assets in comparison to total liabilities.