There is no IRS office in Zambia
For immediate assistance from a taxpayer specialist, you can call, fax or email the Internal Revenue Service (IRS) International Customer Service Site located in Philadelphia. The Service site is open Monday through Friday, for 17 hours each day from 06:00 AM to 11:00 PM, Eastern Time. The customer service representatives there can be contacted as follows:
Tel : 001-267-941-1000
Email enquiries : See IRS page for international tax payers.