In the case of Systematic Investment Plan installments in an equity fund, each installment is treated as a separate purchase, and any unit would have to be held for more than 12 months to qualify as long-term.
Therefore, if an investor redeems all units, only gains from those units that have been held for more than 12 months will qualify as long-term capital gains.
The gains from the remaining units will be short-term capital gains.
Lets consider this example as in this example which is going to be Long term capital Gains and which is going to be short term capital gains if investor decided to sell all units on 10th April 2012
Here in this example SIP is started from 14th July 2008 and it on going sip, if the investor decided to redeem all units then
Units from 14th July 2008 to 15th March 2011 is considered as Long Term Capital Gain/loss
and units from 15th April 2011 to 14th March 2012 is considered as short term capital gain/loss