It depends on your visa expiry date. At the first visit it is either till it is mentioned on your entry stamp or if you haven't got any stamp it is implied you can stay for 6 months. Next expiry on renewal will depend on how long they allow you to stay when you request for extension. In some cases it could be 6 months in others it could be lesser. So you need to apply for extension every time you approach your expiry date.Oh okay, so you will have to renew your spouse`s visitor visa every 6 months?