Hi John, Is the checkbox bound to a field? Do you need to see that field in a table outside the form for any reason?
I assume you mean the current calendar year, so on January 1st we could set the checkbox field with an update query for all the people that would turn 70 before January 1st of the next year?
Or do you want to wait till the form opens the members record, and then do the update to the checkbox field?
If it's a new record in the form, then you'll want to set it AfterUpdate of either the birthdate field or at record update.

Thomas,
Thanks for your reply.
Yes, the check box is bound to a field (Work Exemption). The field is used in calculating dues. Members are required to volunteer 8 hours work per calendar year, else there is a penalty of $25.00 for every hour less than 8. Members that reach the age of 70 are exempt from work time, thus the check box.

Well then, having cleared up some of the questions, do you want to do a query to update all members at once, in case some were missed or wrongly checked, and then modify the form for the future?

It's a concept very similar to why I have the client selection, options and groups in the ADS.
If you care, I'll put together a quick video on how to do it in the evaluation version of ADS, but for my Entity table/form. Then you can do it your way in your forms.

If you know how to implement it in your queries and forms, then here is the simple function/expression:

Details

Public Function fIsWrkExempt(aDtBeg As Date) As Boolean
  'Returns a T/F for anyone with a 70th birthday this year
  fIsWrkExempt = IIf(Year(aDtBeg) <= (Year(Now) - 70), True, False)
End Function
Copy

For those that are new to VBA, it's always a good idea to "validate" (meaning to test) your code.
A good way is to test the extremes of values and expectations.
For simplicity, this function requires a valid date to be passed, or there will be a RTE (run time error).
The image below shows how to do that.

Can some aspiring developer (no veterans) fix the one line of code to handle a Null birthdate?
Answer tomorrow if no one answers correctly.

Thanks Thomas, I will give it a go in a couple days and let you know the end result. Doctors appointments getting in the way.... grrrr...

Well, I misled you, there were TWO lines that needed 'fixing'.
In VBA, you can only pass a Null (from code or data) to a variant variable type.
So, we need to remove 'As Date' in the first line to change aDtBeg to a variant.
Then, we fix the line of code to deal with a null by adding another IIf() function.

The IIf() is great in that you don't need to create an If/Then/Else construct.
While it can be used in VBA, it eliminates the need to write VBA code for queries in that the part to the right of the '=' can be placed directly into an update query, after a preliminary update query makes NO in all the yes/no exempt field in the table that may have errors.

One could run the update query every day, or when the form closes. But that is kind if inefficient, especially in a table with lots of records. Better to write a bit of code in the AfterUpdate procedure of the birth date textbox, using our function to set the [Work Exemption] field.

But why use the fIsWrkExempt() function when a simple line of code could be in the AfterUpdate procedure? Suppose you have code logic in many places in your application (especially if it's more complicated than this example). What if the boss comes out one day and says, 'No more exemptions until they pass their 70th birthday!' Now, all you have to do is modify one function instead of hunting down all the different lines of code (that may not all read the same to accomplish the rule).