Severance and unemployment, do they overlap?

My employer is paying severance in instalments and I am not sure whether to file now. It has been weighing on me all week. I have a mortgage and need to plan. Who should I ask before signing?

I filed on day one anyway and reported the severance honestly. The agency decided what to do about the timing.

Rules differ by state. I called the claims line and asked directly, then wrote down the answer and the date.