In Germany we have a relatively good social security system. If you are unemployed, there are basically two types of unemployment benefits that you can apply to. If you don't qualify for the first one, normal unemployment benefits (ALG1), then you would qualify for the second one (ALG2), which covers people who are not habitual workers.

The ministry of work and the jobcenter (yes, those are two different departments) however utilize a principle called Zuflussprinzip, which means that your eligibility for benefits is based on when you received your last salary as opposed to for which month that same salary was meant to compensate you.

An employer, with whom one might not have parted in good, might delay payment of your salary, so that it arrives on your bank account on the next month, thus making you ineligible to receive unemployment benefits for the first month of your unemployment.

inb4: An application for benefits for the gap month doesn't work for multiple reasons: already employed and/or has to be applied for in advance.

source: Happened to me.