Many thanks but I still can't get it to work so perhaps I gave you the wrong information.
I have set the mysql database fields to DATE
The current form code for I want to change for subscribe date and 1 year later unsubscribe date is:
<input id="HiddenFields_userSubscribeDate" name="HiddenFields_userSubscribeDate" type="hidden" value="<?php echo((isset($_GET["invalid"])?ValidatedField("registration","HiddenFields_userSubscribeDate"):"")); ?>">
<input id="HiddenFields_userExpiryDate" name="HiddenFields_userExpiryDate" type="hidden" value="<?php echo((isset($_GET["invalid"])?ValidatedField("registration","HiddenFields_userExpiryDate"):"")); ?>">
I have tried pasting in the code you provided in to the value = "" but it won't add to the database. Can you advise where I am going wrong. A million thanks