One possiblity is that the agreement was for non-decductible alimony and having the payment funded by a QDRO would shift the incidence of taxation to the ex-spouse.
The finance secretary also told the committee that with the volatility on income tax revenues, there had to be sufficient protection to cope and that without that protection there was "undoubtedly a possiblity to be worse off".
Lib Dem MP Alistair Carmichael questioned why Mr MacAskill had gone to speak to Mr Al-Megrahi directly, rather than through his legal team, and wondered if he would do this every time that there was the possiblity of an early release or transfer agreement.