PKNIC is a global registrar for all the domains relevant to .pk. As per their rules, the pk domain can be registered for a minimum of two years. So either it is .pk, com.pk, or .edu.pk, it has to be registered for at least two years. At the same time, a .com domain is registered minimum for one year. As a .pk domain is registered for two years, so when we compare the costs with the .com domain that is registered for one year, we can see that .pk is less expensive as a whole.