For determing the safe and unsafe harbor percentages for rate group testing, is it permissible to round the NHCE concentration percentage to the nearest whole percentage?

For example, the NHCE concentration percentage is 74.74%. Should I use the safe and unsafe harbors for 74% or 75%.

Thanks.

You should always round down when using the table in the 410(B) regs. The safe harbor percentage as defined in 1.410(B)-4©(4) is 50, minus 3/4 of a percentage point for each whole percentage point by which the NCE concentration percentage exceeds 60. In your example, a 74.74 concentration percentage would give a safe harbor percentage of 50.00-.75(14) or 39.50, which is the safe harbor percent for a concentration percentage of 74 in the table.