When the income behind the payment disappeared
Job loss, cut hours, a business that slowed, or a contract that ended. The mortgage was affordable on the old number and is not on the new one. What matters most here is whether the gap is temporary or permanent, because that answer selects the option.

What you might be thinking
- I will be working again soon, I just need to get through this
- I took a job that pays less and I cannot make it work
- I am self employed and they keep asking for documents I do not have
All three come up on almost every call. None of them is a silly question.
What actually matters here
Temporary and permanent take different paths
A gap with an end date suits forbearance or a repayment plan. A permanently lower income needs a modification or an exit. Be honest with yourself about which one you are in.
Self employed income is documentable
Servicers ask for profit and loss statements, bank statements and tax returns rather than pay stubs. It is more paperwork, not an impossibility, and the first request is rarely the complete list.
Unemployment income counts
Some programs will consider unemployment benefits as qualifying income. Do not assume you have nothing to show.