In plain English
FAR 52.216-31, Time-and-Materials/Labor-Hour Proposal Requirements—Commercial Acquisition, is a solicitation provision prescribed at FAR 16.601(f)(3), most recently dated Nov 2021. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
This is a solicitation provision — it applies to offerors when submitting an offer, not to contract performance, so subcontract flowdown is generally not the operative question for it.
Where it's prescribed
As prescribed in 16.601(f)(3), insert the following provision:
Prescribing reference: FAR 16.601(f)(3).
The official text, verbatim
As prescribed in 16.601(f)(3), insert the following provision:
Time-and-Materials/Labor-Hour Proposal Requirements—Commercial Acquisition (Nov 2021)
-
(a) The Government contemplates award of a Time-and-Materials or Labor-Hour type of contract resulting from this solicitation.
-
(b) The offeror must specify fixed hourly rates in its offer that include wages, overhead, general and administrative expenses, and profit. The offeror must specify whether the fixed hourly rate for each labor category applies to labor performed by-
-
(1) The offeror;
-
(2) Subcontractors; and/or
-
(3) Divisions, subsidiaries, or affiliates of the offeror under a common control.
-
(End of provision)