Cost share (mandatory)

Mandatory cost share is the portion of project cost a sponsor requires the recipient (or a third party) to contribute as a condition of accepting the award, rather than a contribution the recipient chooses to offer. The requirement is set before the application stage — in the authorizing statute, the notice of funding opportunity, or the award’s general terms — and it is not something a proposal writer can decline to include once the programme requires it.

Where the requirement comes from

Mandatory cost-share percentages are program-specific, not universal. NSF’s Major Research Instrumentation programme has historically required a fixed institutional cost-share percentage; Horizon Europe co-funded partnerships require participating national funders to match the EU’s contribution at a set ratio. Because the figure varies by programme and can change between funding cycles, the applicable percentage should always be confirmed against the current notice of funding opportunity rather than assumed from a prior award.

What counts, under 2 CFR 200.306(b)

For US federal awards, contributed funds only qualify as cost share if they are verifiable in the recipient’s records, not already claimed against any other federal award, necessary and reasonable for the project’s objectives, allowable under the cost principles, not otherwise paid by the federal government (absent a specific statutory exception), and provided for in the approved budget when the agency requires that. A contribution that fails any one of these tests cannot be counted toward the commitment, even if it was genuinely spent on the project.

The risk of under-delivering

Because a cost-shared project’s funder share is frequently calculated as a percentage of total approved cost — sponsor funds plus the required match — falling short of a committed mandatory amount is a compliance shortfall against the award terms, not a private institutional matter, and a shortfall caught at closeout is far costlier to resolve than one corrected mid-project.

How it differs from voluntary cost share

Mandatory cost share is required regardless of what the applicant proposes; voluntary cost share is offered by the applicant to strengthen a proposal where the sponsor does not require it — federal policy under 2 CFR 200.306(a) actively discourages funders from soliciting the latter for merit review of federal research grants.

Checking this against the current guidance

The mandatory cost-share percentage, and what happens to it if your award is later modified, is set by your specific program’s funding opportunity, not by 2 CFR 200 alone. The answer depends on which program’s notice of funding opportunity you are working to, and the page above states the general rule.

Ask CASRAI: If our mandatory cost-share match is calculated as a percentage of total approved project cost, what happens to the required match amount when the award is later modified — extended at no cost, reduced in scope, or increased — and whose job is it to catch the recalculation?

It searches CASRAI’s indexed corpus of research-administration guidance and cites the passage behind each claim, so you can open the source and check it rather than take its word — and it says so when the corpus does not cover something instead of guessing. Two questions a day are free while you are signed out, no account and no card. Everything CASRAI publishes stays free to read.

Frequently asked questions

If our mandatory cost-share match is a percentage of total project cost, what happens when the award is later modified?

Because the match is proportional to total approved cost rather than a fixed number, any change to the award’s total approved cost — a no-cost extension that adds activity, a reduction in scope, a supplemental award — changes the dollar match required to stay in compliance. Nothing in 2 CFR 200.306 recalculates it automatically: that is the recipient’s own sponsored-programs office responsibility, and it is exactly the kind of gap a Single Audit or closeout review is positioned to catch if nobody tracks it proactively.

Can a subrecipient’s cost share count toward the prime recipient’s mandatory match?

Only if it independently passes the same 200.306(b) tests — verifiable, not claimed elsewhere, necessary and reasonable, and documented in the approved budget. A subrecipient’s contribution does not automatically count just because it flows through the prime’s award.

Does a program’s mandatory cost-share percentage ever change between funding cycles for the same agency?

Yes. Mandatory percentages are program-specific and set in the current notice of funding opportunity, not fixed indefinitely; NSF’s Major Research Instrumentation program and Horizon Europe co-funded actions are two examples where the applicable ratio should be confirmed against the live solicitation rather than assumed from a prior award cycle.