Question: If I have my  current plan and want to upgrade to a bigger plan, can I just pay the remaining amount and upgrade my plan?

Answer: In that case, you can just top-up and purchase additional/extra forms in the future. 

Discount is also applied according to your plan subscription. I'm just waiting for the management how much is the cost for the new package-"Standard" extra forms. 

Below pricing will show that the higher the package the lower the cost of the "extra form".

We can't manipulate the system for an upgrade, the whole system is automated and we don't have developer bandwidth yet to manage this stuff in a manual ad hoc way:

Option:

a. Buy the bigger package now. 

b. Buy the smaller package and buy extra forms / pay-as-you-go

c. Buy the smaller package. use the forms up and then buy a bigger package*

*If you used up your C,P,T,S and still has "all other small forms" left what you can do:

a. Buy extra C,P,T,S and finish the smaller forms

b. Simply buy a whole bigger package & forget the smaller forms left (ie ITR & AS)