To amend title XI of the Social Security Act to require the Secretary of Health and Human Services to follow rulemaking procedures for costly Medicaid subregulatory policies.

Better Accounting for Medicaid Costs Act of 2017 This bill amends title XI (General Provisions) of the Social Security Act to require the Centers for Medicare & Medicaid Services (CMS) to follow rulemaking procedures with respect to certain Medicaid subregulatory policies. Before issuing a Medicaid subregulatory policy, CMS must determine the extent to which the policy is projected, with respect to each year in a 10-year period, to increase state or federal expenditures under the Medicaid program. If the policy is projected to increase expenditures by an amount exceeding a specified threshold, CMS may implement the policy only through notice and comment rulemaking.