There is a time bud of paying the penalties if found wrongly done in tax. But, if the period exceed the time bud and there is an error, they cant make you pay .. only within the stipulated time frame ...

Also why need to claim and max out all ... if company already do MTD from the salary, some amount of claims will already allowed you to have a small value of refund .. unless you want more refund in which they will start to audit ...