What should I check about income if illness or injury keeps me from working?
The short answer
Start with what you already have: savings, paid leave, and any disability benefits through work or an individual policy. Disability insurance can replace part of your earnings when a covered illness or injury prevents you from working. The policy's definition of disability matters; difficulty doing your current job is not always enough to qualify.
What you can check privately
Check four things in the actual documents: what qualifies, how long you wait before benefits start, how much could be paid, and how long payments could continue. Also check whether other benefits reduce the amount. Those details can differ between policies.
A useful next step is to place those amounts and dates beside the bills you would still need to pay. That can show what is already handled and what remains uncertain without assuming you need another policy. This answer concerns your own inability to work; taking time off to care for someone else is a different question.