Question about reporting foreign income for US Citizen living and working in Switzerland - before or after witholding?

I began to live and work in Switzerland last year and Swiss taxes are witheld from every paycheck (Quellensteuer).  I will not file a Swiss tax return for last year and don't expect any refunds, so when I report my foreign income to the IRS (i.e. Form 2555, field 19) will that amount be before or after the witholding tax?  Or is it more complex?  Thanks!