A1: start_date
B1: workdays
C1: deadline
H1: excluded_dates
A2: =DATE(2026,9,4)
B2: 3
H2: =DATE(2026,9,7)
H3: =DATE(2026,9,10)
C2: =WORKDAY(A2,B2,$H$2:$H$3)
Format A2, C2, H2:H3 as yyyy-mm-dd.
Expected C2: 2026-09-11