Before Pesach
Utensils used during the year generally require kashering before Pesach, unless they are designated exclusively for Pesach use. Utensils must be cleaned thoroughly beforehand, followed by the halachic kashering process appropriate to their usage.
After Non-Kosher or Improper Use
If a utensil was used with non-kosher food, meat and dairy were heated together, kashering may be required. Cold use is governed by different halachic rules than hot use, and each situation must be assessed carefully.
Changing Kitchens or Kashrut Standards
Utensils brought from another home or kitchen with different kashrut standards may need kashering before use, depending on prior supervision and usage history.
Long Periods of Non-Use
In some cases, utensils that were unused for an extended period may have different halachic considerations. This is not a general rule and requires clarification based on the specific circumstances.
Nachman Harris. Kosher Expert.
Available for any of your questions
