When a company issues the shares and  it asks the subscribers to pay  certain amount at the time of subscription the shares, that is called as called up capital.  The called up amount may as fully paid or in part.

For example:- a company issued one lac shares of 10 rupees each and asked to the subscribers to pay 5 rupees per share. In this case the called-up capital will rupees 5 lac, though the value of shares is 10 lac rupees. In the same example suppose the company  asks to pay Rs.10 per share at the time of allotment of shares then the called-up capital will be 10 lac rupees.