What happens if Congress doesn't raise the debt ceiling? What you need to know about the showdown between Democrats and Republicans

The debate over the debt limit — often called the debt ceiling — is heating up again on Capitol Hill. But government officials, business leaders and economists are raising the alarms, saying not addressing it in a timely manner would be disastrous. 

The limit is the maximum amount the United States is allowed to borrow to pay its debts. If the amount of government debt hits that limit, and doesn't lift the ceiling, the U.S. would be unable to pay what it owes and could default. When Congress raises or suspends the debt limit, it's not greenlighting new spending — instead, it allows the Treasury to pay for spending it already approved.