Prepaid

sure, it should be treat as advence money paid in advance for the rest of the period, for which service is not yet received. 

date of receipt of invoice ?

1) 1-1-2018 AMC charges A/c (2016-17)             Dr.  <first 6 months amount>

                   AMC charges A/c (2017-18)             Dr.  <last 6 months amount>

                          To vendor A/c                                                      <12 months amount>     

2) 30-06-2018 first 6 months amc charges is to be debited to profit and loss a/c 

                    profit and loss A/c                         dr.  <first 6 months amount>

                                To AMC charges                                                <first 6 months amount>

3) 30-9-18 on payment of liability 

                   Vendor a/c Dr                        <12 months amount)>

                              To Bank a/c

4) 31-12-18 finally AMC charges for 2017-18 charged to profit and loss a/c

most wellcome Mr. krishna