Zero-Baseline Budget Act of 2018 This bill amends the Balanced Budget and Emergency Deficit Control Act of 1985 to change the assumptions that the Congressional Budget Office uses to calculate the baseline for discretionary spending. (A baseline is a projection of federal spending and receipts during a fiscal year under current law.) The bill changes the assumptions used for the discretionary spending baseline to eliminate adjustments required under current law for inflation, expiring housing contracts, social insurance administrative expenses, pay adjustments, and changes to other personnel benefits. The bill also prohibits adjustments for inflation or any other factor.