Payer of last resort
What every state victim compensation program is. It pays what insurance and other sources do not, which means you file both rather than choosing between them, and the program will ask what insurance already covered.
What kind of thing this is
Payer of last resort is an insurance concept in this field. This definition comes from a primary government source. Where the wording matters we quote the standard rather than paraphrase it, because paraphrase is where precision leaks out.
Where you will meet it
You will hear this from an adjuster, and it usually decides the answer rather than describing it. Getting the term right is how you ask a question the adjuster can actually answer.
Why the wording matters
This site defines terms in under forty words wherever it can, and attaches the practical consequence rather than leaving it implied. A definition that tells you what something is, without telling you what follows from it, is trivia at a moment when nobody has room for trivia.