[afraidfortherepublic]

(What kind of silly notion requires that write-in candidates register in the first place!)

That is the law in WI. A write in candidate who wants to be seriously considered must register with the clerk of the entity in charge of the election -- either city, county, or school board -- if he/she wants any votes they get actually counted. Spur of the moment write-ins are recorded, but not counted.

[grassboots.org]

How much notice do they have to give?