DateTime utcDateTime = new DateTime(databaseDateTime.Ticks, DateTimeKind.Utc);

DateTime utcDateTime = DateTime.SpecifyKind(databaseDateTime, DateTimeKind.Utc);

DateTime utcDateTime = databaseDateTime.ToUniversalTime();

public partial class Person {

  partial void OnLoaded() {
    this._BirthDate = DateTime.SpecifyKind(this._BirthDate, DateTimeKind.Utc);
  }
}

TimeZoneInfo UTCTimeZone = TimeZoneInfo.FindSystemTimeZoneById("UTC");
DateTime utcTime = TimeZoneInfo.ConvertTimeToUtc(myLinq2SQLTime, UTCTimeZone);

public partial class Person
    {
        protected override void OnPropertyChanged(string property)
        {
            if (property == "BirthDate")
            {
                this._BirthDate= DateTime.SpecifyKind(this._BirthDate, DateTimeKind.Utc);
            }

            base.OnPropertyChanged(property);
        }

    }

DateTime utcDateTime = DateTime.SpecifyKind(databaseDateTime, DateTimeKind.Utc);

<#+ if( ((PrimitiveType)primitiveProperty.TypeUsage.EdmType).PrimitiveTypeKind == PrimitiveTypeKind.DateTime)
            {
#>
        if(<#=code.FieldName(primitiveProperty)#> == new DateTime())
        {
            <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
<#+
            if(ef.IsNullable(primitiveProperty))
            {
#>
            if(value != null)
                <#=code.FieldName(primitiveProperty)#> = DateTime.SpecifyKind(<#=code.FieldName(primitiveProperty)#>.Value, DateTimeKind.Utc);
<#+             }
            else
            {#>
            <#=code.FieldName(primitiveProperty)#> = DateTime.SpecifyKind(<#=code.FieldName(primitiveProperty)#>, DateTimeKind.Utc);
<#+
            }
#>
        }
        else
        {
            <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
        }
<#+
        }
        else
        {
#>
    <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
<#+
        }
#>

TimeZoneInfo cet = TimeZoneInfo.FindSystemTimeZoneById("Central European Standard Time");
ac.add_datetime = TimeZoneInfo.ConvertTime(DateTime.Now, cet);