When the government passes a new law that explicitly changes overall tax or spending levels, it is enacting:

A discretionary fiscal policy.

Explanation:

A discretionary fiscal policy is a policy guideline out in place by Government with the aim of either shrinking or expanding the economy. This kind of policy is usually associated with either an increase or decrease in the tax rates or levels which will increase government revenue or decrease in government revenue or be focused on increasing or decreasing government spendings on the economy either through increasing or decreasing investment in infrastructures etc