Sometimes you may want the text from a validation control to appear below a control such as a TextBox rather than next to it. So you might find yourself adding a <BR /> tag between the TextBox control and the Validation Control. However, you later realize that the <BR /> tag causes unwanted white-space or alignment issues even when the validation text is not displayed. If so, try adding the <BR /> tag to the beginning of the Validation Control text itself.

For example rather than….

Notice that the <br /> tag has been moved to inside the ErrorMessage attribute text. This way the tag is emitted and effects formatting only when the error text is displayed. When using client-side validation, be sure to set Display="Dynamic", otherwise the text will be marked as hidden using CSS but the break tag will still be in effect in the HTML.