You are not US citizen until after your oath ceremony. Requirement for fed job is US citizenship, so you will not be allowed to work after filling N400(?).
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arkAug 29, 2019 4:20 PM
A green card holder actively seeking citizenship can apply for federal employment. N300 proves you intend to become a USC one day but doesn’t prove you are seeking citizenship, so filing N300 doesn’t allow you work for federal jobs.
Filing N400 within 6 months of being eligible to file will allow you work for federal jobs with pending N400.