main.cpp:

CAmount GetBlockValue(int nHeight, const CAmount& nFees)
{
    //...
    } else if (nHeight > 1400000) {
        int halvings = nHeight / Params().SubsidyHalvingInterval(); // 675000 blocks or 6 months
        // Force block reward to zero when right shift is undefined.
        if (halvings <= 64) {
            nSubsidy = 10 * COIN;
            nSubsidy >>= halvings;
        }
    }
}
return nSubsidy + nFees;