I'm Confused from the fact that Vlan tagging is done at access port and trunk port always gets tagged packets (until its case of native vlan).But I still believe in other fact which says tagging happen only when a frame hit the trunk port which means trunk port gets untagged frame and tagging is not possible at access port.

Would like to know where actually this tagging happens ?

and also which command we can use to encapsulate 802.1q protocol to access port ? The way we do at trunk port is

switchport trunk encapsulation dot1q

Is the above command applicable for access mode also?