What do you mean by this?
In my case I own 4 funds (now 3).
1) FOORD equity fund - does ok, costs a lot so I'd like to get rid of it.
2) STXIND - does very well, I'll keep this for a long long time.
3) GIVIND - does ok, but I think it's currently too heavy into MTN, and I'd prefer to put that money somewhere else.
4) DIVTRX - still new but the index has done extremely well. It also pays a pretty good dividend and is well diversified.
So I'd like to get rid of as much of 1) and 3) and put it into 4. Problem is, if you sell I need to pay a lot of capital gains tax. But now, the whole market is cheap, so for example if I sell GIVIND for a 10% loss, I can also buy DIVTRX at a 10% discount, so in effect there's no loss, just a re-balancing. But to SARS there is a loss, so I can take the amount of that loss, and sell some of my FOORD, and even though I make a profit, it's cancelled out by the GIVIND loss and I won't pay tax on it.