A change in how the government estimates health insurance costs is expected to give a slight boost to a popular U.S. inflation measure, reversing a trend that had been providing some relief in recent months.

Beginning with Tuesday's release of the October consumer price index (CPI), the Bureau of Labor Statistics (BLS) will roll out a few changes to how it tabulates the category. In addition to a routine change in source data, the new methodology will aim to smooth some of the volatility and reduce time lags in the index.

After being a reliable drag on overall inflation for the past year, the new computation is widely anticipated to put upward pressure on the headline CPI, at least in the near term. It'll also boost a narrower subset of services inflation that excludes energy and housing.