Add 12 days on Anniversary

Hi,

Client's requirement is to have 1day/month; but for every anniversary, they need to accrue additional 12 on the anniversary date.

Can some one suggest us any idea on achieving this requirement?

We already have an idea to automate HDL load of 12days on anniversary dates;

Does anyone have any logics to acheive it directly through FF?

We thought we will give plan term as Anniversary so that Carryover will be done on anniversary date and +12 will done to the Carryover balance; but seems it is not possible to add 12 to actual Carryover balance.

Can anyone suggest is there any possibility to make