It was supposed to be the sweetener to make the bitter pill of asset sales easier to swallow. It was supposedly going to funnel the billions of dollars from those sales into building a better economic and social infrastructure by way of modern schools, hospitals, roads, rail and so forth.
And to a large degree, National's grandly-titled Future Investment Fund has done exactly that. But this big pot of money has ended up being dipped into by National for purposes which would seem to fall way outside parameters pegged out by John Key when he unveiled the concept.
He intimated the fund would be dedicated solely to capital projects, rather than day-to-day operational spending. It would avoid a cash-strapped Government having to borrow. It was thus widely assumed the money from National's partial privatisation programme - an estimated $5 billion to $7 billion - would all be poured into fixing the country's infrastructure.
However, a Treasury document obtained by Labour details a host of "initiatives" in this year's Budget which would be paid for by the fund, but which seem to run counter to the kind of things which Key gave the impression would fall under the fund's ambit.
It is drawing a very, very long bow to argue that the start-up costs of Paula Bennett's white paper on vulnerable children, or recompensing employers for the costs of beneficiaries' failed drug tests, or beefing up the "security and risk management" of the Prime Minister's department can somehow be classed as capital spending.
Admittedly, the amounts devoted to those items are tiny in comparison to the $1 billion earmarked from the fund for new schools or the fund's $426 million contribution to the building of new hospitals in Christchurch.
Labour naturally dismisses the fund as a slush fund. That may be going a bit too far.
It is not (yet) quite in the category of pork-barrel politics either. Some money from the fund has gone into projects which might be seen as non-political, such as the refurbishment of the National War Memorial and the closed captioning of Parliament TV for the deaf and hard of hearing.
Still the fund is proving to be a very golden goose for National. But it is one which - according to another Treasury paper - could be quickly killed off by even modest amounts of capital being sucked into ongoing operational spending.