Formatting picklist, checkbox and date values in import files
Key Takeaway
Use 1 and 0 for checkboxes, and put multi-select picklist values in one column separated by semicolons. Format dates the way Salesforce displays them for the locale of the user running the import.
When you import data, each value in your file must use a format that the target field type understands. Checkbox, picklist, multi-select picklist, and date/time fields each have their own rules. A wrong format can change a value, replace it with a default value, or leave the field blank.
Checkbox values
To import into a checkbox field, use 1 for checked and 0 for unchecked. A record with 1 in the column imports as checked. A record with 0 in the column imports as not checked.