 <p>Replace every occurrence of TODAY() with DATE(2011,9,1):</p> <pre><code>=YEAR(DATE(2011,9,1))-YEAR(C2)-1 + (MONTH(DATE(2011,9,1))&gt;MONTH(C2)) + (MONTH(C2)=MONTH(DATE(2011,9,1)))*(DAY(DATE(2011,9,1))&gt;=DAY(C2)) </code></pre> <p>For a person born on the date in cell C2, this would give what their age will be on Sept 1, 2011.</p> <p><strong>Edit:</strong> Or, more simply, try this:</p> <pre><code>=2011-YEAR(C2)-1 + 9&gt;MONTH(C2) + (MONTH(C2)=9)*(1&gt;=DAY(C2)) </code></pre>