It is my understanding I can configure AutoMapper in the following way and during mapping it should format all source model dates to the rules defined in the IValueFormatter and set the result to the mapped model. ForSourceType<DateTime>().AddFormatter<StandardDateFormatter>(); ForSourceType<DateTime?>().AddFormatter<StandardDateFormatter>(); I get no effect for my mapped class with this. It only works when I do the following: Mapper.CreateMap<Member, MemberForm>().ForMember(x => x.DateOfBirth, y => y.AddFormatter<StandardDateFormatter>()); I am mapping DateTime? Member.DateOfBirth to string MemberForm.DateOfBirth. The formatter basically creates a short date string from the date. Is there something I am missing when setting the default formatter for a given type? Thanks public class StandardDateFormatter : IValueFormatter { public string FormatValue(ResolutionContext context) { if (context.SourceValue == null) return null; if (!(context.SourceValue is DateTime)) return context.SourceValue.ToNullSafeString(); return ((DateTime)context.SourceValue).ToShortDateString(); } }