SCHEDULE 12  Article 11  Modifications to licences granted to authorised transmitters:  modification to condition C21  ( a ) Condition C21 was inserted into the standard conditions of licences of authorised transmitters by article 8 of, and Schedule  7 to, the 2005 Order.  5 5.  In paragraph 9—  “ 5A.  For each relevant year beginning on or after 1 April 2021, the statement made  pursuant to paragraph 5 shall also set out:  4.  After paragraph 5 insert—  “ 3A.  For each relevant year beginning on or after 1 April 2021, each invoice  issued to an authorised supplier pursuant to paragraph 3 must also include a separate  amount determined by applying the Shetland p/kWh tariff determined in accordance  with paragraph 2A to the units of electricity actually supplied by that authorised  supplier during each period in relation to the relevant year t specified in the table in  paragraph 2.”.  3.  After paragraph 3 insert—  “ 2A.  For each relevant year beginning on or after 1 April 2021, the licensee shall  calculate a Shetland p/kWh tariff by dividing the total Shetland assistance amount by  a reasonable forecast of the total units of electricity to be supplied within Great  Britain during the relevant year.”.  2.  After paragraph 2 insert—  1.  Condition C21 (assistance for areas with high distribution costs scheme: payments  from authorised suppliers)( a ) is modified as follows.  (a) the methodology used to calculate the Shetland p/kWh tariff;  (b) the Shetland p/kWh tariff that will apply in the relevant year;  (c) a statement of the Shetland assistance amount payable by the licensee in  relation to the relevant year, together with details of the payments payable  by the licensee on the payment dates in relation to the relevant year  specified in standard condition C22.”.  (a) in the definition of “assistance amount” after “pursuant to” insert “paragraph 1 of”,  (b) after the definition of “relevant year” insert—  ““Shetland  assistance amount”  means the amount payable by the licensee to a relevant  distributor in any relevant year beginning on or after 1  April 2021 made pursuant to paragraph 1A of standard  condition C22 (Assistance for areas with high  distribution costs scheme: payments to a relevant  distributor).  “Shetland p/kWh  tariff” means the tariff calculated in accordance with paragraph  2A.”. 