Validation rule to restrict a date pick to be at least 10 business days in the future

[Jonathan Saldarriag]

I am trying to set a validation rule for a date field called deadline. The field is controlled by another one that has only two options (newCustomer, existingCustomer). What I want to achieve is:

If newCustomer is selected the user cannot select today as the date (this is working fine). If existingCustomer is selected then the user should have a block of 10 business days and only the day after can be selected. Right now, I have set up two rules definitions where the validation code is as follow:

deadlineSubmission:<([today]+10)) AND typeCustomer:existingCustomer AND typeAssessment:ITsecurity

It only works for calendar days only. I want to be business days rather.