Legislative economists had projected that, under Referendum C, the state would collect $3.6 billion more over five years than it otherwise would have if refunds were required. The state did collect that amount, but it did so in the first three years of Referendum C, with revenues falling so far in the last two fiscal years that the state retained no additional revenue.
Current projections show that, under the new Referendum C revenue limit, the state will retain $748.4 million in the current fiscal year that it would have had to refund to taxpayers if the old TABOR limit had been in place. Under the new limit, the state budget would have to grow by $1.4 billion before refunds were required.
Voter approval is still required for tax increases (as opposed to revenue increases or tax benefit abolition), so the legislature can take advantage of reset TABOR revenue limits to pass new taxes.
The problem at the moment for Colorado's state budget is a projected shortfall of $1 billion in a $7 billion general fund budget for the current fiscal year, rather than excess revenue.