str_signed_date = "8/12/2024"
str_start_date = "1/8/2025"
signedDate = DateTime.ParseExact(str_signed_date, "M/dd/yyyy", System.Globalization.CultureInfo.InvariantCulture)
startDate = DateTime.ParseExact(str_start_date, "M/dd/yyyy", System.Globalization.CultureInfo.InvariantCulture)
rangeStart = signedDate.AddDays(-15)
rangeEnd = signedDate.AddDays(15)
If startDate >= rangeStart AndAlso startDate <= rangeEnd
// str_start_date falls within 15-day range of str_signed_date
Else
// str_start_date does not fall within 15-day range of str_signed_date
End If
LLM helped me to write this but I think this should work.