The federal model provides that the government will return 90% of the revenues generated by the tax to taxpayers. Those rebates are paid to taxpayers slightly in advance.
Therefore, if the total amount of rebates to taxpayers is higher than the amount the government is able to obtain through the tax, future rebates will have to be reduced accordingly to ensure that the 90% is met.
If the government ever decides to freeze the amount of rebates or still make the scheduled payments, there will have to be a mechanism to pay back the difference or make up the shortfall.