Microsoft Access Developer Question:

By default, Access waits until you press Enter before it selects the Next control on your form. However, this is a wasted keystroke you can eliminate by setting each control's Auto Tab property to Yes. This Property also requires that you set an input mask. Once the data you're entering satisfies the input mask, the Auto Tab property Automatically selects the form's next control. We don't recommend you Use this feature unless you can apply it consistently; otherwise you'll just confuse your users, who won't know when to press Enter.