NSF Budget Preparation Guide 2026: All Rules

NSF budget preparation looks straightforward until you hit the rules that are different from every other federal agency. The two-month salary cap doesn't exist at NIH. The participant support cost protections don't apply at DOD. The equipment threshold matters more than you think. And the Research.gov budget module enforces some rules automatically while leaving others for you to get wrong on your own.

The same mistakes come up over and over. A PI charges three months of salary because that's what they did on their NIH grant. A postdoc's fringe rate is calculated wrong. Participant support costs get lumped into "other" without the required justification. These aren't scientific problems; they're mechanical problems that waste time and sometimes kill proposals.

This guide covers every NSF budget category in detail, with specific attention to the rules that differ from NIH and DOD, the mistakes that trigger compliance returns, and how to use Research.gov (opens in a new tab) to build your budget correctly.

NSF Budget Categories: The Complete Breakdown

Every NSF budget uses the same category structure, whether you're requesting $50,000 for a conference grant or $5 million in FY2025 for a center. Here's each category and what belongs in it.

A. Senior Personnel

Senior personnel includes the PI, co-PIs, and other senior researchers named on the proposal. This is where the two-month salary cap applies.

The Two-Month Rule

NSF limits the total salary that any individual can charge across all NSF-funded projects to two months per year. This is a person-level cap, not a project-level cap.

How to calculate: Your institution's base salary divided by the number of months in your appointment (typically 9 or 12) gives you the monthly rate. For a 9-month faculty member earning $108,000, one month of summer salary is $12,000. Two months maximum from NSF is $24,000.

For 12-month employees: The calculation works the same way. $120,000 annual salary / 12 months = $10,000/month. Two months maximum = $20,000 from NSF.

Common mistake: PIs who have multiple active NSF awards forget to add up their total salary across all of them. NSF audits this through the Current and Pending Support document, and inconsistencies between your budget and your C&P trigger compliance questions.

Going above two months: The PAPPG doesn't limit exceptions to programs that name one. According to NSF's PAPPG, any compensation above two months for a senior person must be disclosed in the proposal budget, justified in the budget justification, and specifically approved by NSF in the award notice budget. After an award, your institution can rebudget effort above two months without NSF prior approval as long as the project's objectives and scope don't change. If you're budgeting an active EPSCoR competition, compare the solicitation with the live EPSCoR Research Incubators for STEM Excellence page. Without that disclosure, justification, and approval, plan on the two-month cap.

B. Other Personnel

This category covers everyone who isn't a senior person: postdocs, graduate students, undergraduate students, research technicians, and administrative staff.

Graduate student tuition: NSF allows tuition as a direct cost if it's the institution's standard practice. Include it under "Other Direct Costs" rather than under personnel. Check with your SPO about institutional policy.

Postdoc salary: NSF doesn't have a formal postdoc salary minimum like NIH's NRSA scale, but reviewers and program officers notice if your postdoc budget is unusually low. Budget competitive salaries.

C. Fringe Benefits

Fringe benefits are calculated as a percentage of salary and cover health insurance, retirement contributions, Social Security/Medicare, disability, and other benefits. Your institution sets the fringe rates, and they're typically different for faculty, postdocs, graduate students, and undergraduates.

Use your institution's approved rates. These are part of your institution's negotiated rate agreement with the federal government. Don't estimate; get the exact rates from your sponsored programs office.

D. Equipment

Equipment is defined as tangible personal property with a useful life of more than one year and an acquisition cost of $10,000 or more per unit.

Why the threshold matters: Equipment is exempt from indirect costs. A $9,999 item classified as "supplies" has indirect costs charged on it (often 50%+ of direct costs). A $10,001 item classified as "equipment" does not. This can mean a $2,000+ difference in your budget for a single item.

Your institution's threshold may be lower. If your institution defines equipment at $5,000 rather than NSF's $10,000, use the institutional threshold. Items between your institutional threshold and $10,000 are listed as equipment for budget purposes but are still subject to your institution's asset management policies.

Don't game the threshold. Bundling supplies to hit $10,000 or splitting equipment to stay below it is a compliance risk. Budget items at their actual cost.

MRI vs. regular equipment: If a single instrument costs $100,000 or more, consider the MRI program instead of including it in a standard grant budget. Program officers will question equipment lines over $100,000 on standard grants. NSF didn't accept MRI proposals in the FY2026 window (October-November 2025); its MRI update (opens in a new tab) says the next window is planned for October 15 to November 16, 2026. Before you leave the budget stage, review the live Major Research Instrumentation Program page so the cost-share rules, track limits, and submission path match the proposal you are building.

E. Travel

NSF budgets include two travel categories: domestic travel and international travel (formerly called foreign travel). Budget them separately.

What's allowed:

• Conference travel (registration, airfare, hotel, per diem)
• Travel to field sites for data collection
• Travel to collaborator institutions
• Travel to NSF for reverse site visits or meetings (if applicable)

Per diem rates: Use the GSA per diem rates (opens in a new tab) for domestic travel and the State Department rates (opens in a new tab) for international travel.

Fly America Act: If using federal funds for international travel, you must use a U.S. flag carrier or an airline covered by Open Skies agreements. This is a real compliance requirement that gets audited.

Budget tip: If you know which conferences you'll attend, name them and provide estimated costs. "Two domestic conferences at $2,000 each" is more credible than "$4,000 for travel."

F. Participant Support Costs

This is the budget category that's most different from NIH and DOD. Participant support costs are a protected category at NSF.

What counts as participant support:

• Stipends paid to workshop or training participants (not employees)
• Travel for participants to attend your event
• Subsistence (meals, lodging) for participants
• Registration fees for participants

What doesn't count:

• Salary for PIs, postdocs, or students working on the project (that's personnel)
• Travel for PI to attend conferences (that's travel)
• Food at project meetings where attendees are project team members

The protections:

1. No indirect costs. Participant support costs are excluded from the base on which your institution calculates indirect costs. This saves real money.
2. No reallocation without permission. You cannot move money from participant support to other budget categories without written NSF approval. If you budgeted $30,000 for a summer workshop and only spent $20,000, you can't move the remaining $10,000 to buy supplies.
3. Must go to participants. The funds must directly benefit the participants, not the project team.

Common use cases: REU programs, summer workshops, conference grants, training programs, and broadening participation activities. If your broader impacts include a training event for students, the costs should go in participant support.

G. Other Direct Costs

This is the catch-all category for everything that doesn't fit elsewhere:

Subawards deserve special attention. When you include a collaborator at another institution, their entire budget (personnel, fringe, travel, supplies, their indirect costs) goes under subawards in your "Other Direct Costs" section. The first $50,000 of each subaward is subject to your institution's indirect cost rate, per 2 CFR 200.1 (opens in a new tab). Everything above $50,000 is not. Grantsights checked this threshold against the current text of 2 CFR 200.1, which took effect October 1, 2024.

This means subawards can be strategically useful for managing budget structure, but don't create artificial subawards to reduce indirect costs. NSF and your institution's auditors will notice.

H. Indirect Costs (F&A)

Indirect costs (also called facilities and administrative costs, or F&A) are your institution's overhead charge. Your institution has a federally negotiated indirect cost rate that applies to a defined base, usually modified total direct costs (MTDC).

What's excluded from MTDC (not charged indirect costs):

• Equipment ($10,000+ per unit)
• Participant support costs
• Subaward amounts above $50,000 per subaward
• Tuition (at many institutions)
• Capital expenditures

Typical F&A rates: 40% to 65% for research universities. Lower for PUIs and nonprofits. If your institution doesn't have a negotiated rate, you can use the de minimis rate of 15% of MTDC, updated from 10% under the 2024 revision to 2 CFR 200.

Use your negotiated rate unless your institution says otherwise. Federal agencies generally must accept your negotiated rate. Whether you can request less is an institutional decision, so check with your sponsored programs office before changing it.

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NSF Budget Preparation vs. NIH: The Differences That Matter

If you're coming from NIH, these are the rules most likely to trip you up during NSF budget preparation:

The biggest trap: NIH PIs who charge 3 to 6 months of salary on NIH grants will instinctively budget the same on NSF. The two-month cap applies immediately and across all NSF awards. If you already have one NSF grant charging 1.5 months, your new proposal can only charge 0.5 months unless you disclose, justify, and get NSF approval for more.

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The Research.gov Budget Module

All NSF proposals are submitted through Research.gov (opens in a new tab), and the budget module is where you enter your numbers. Here's what you need to know.

What Research.gov Enforces Automatically

• Missing fringe benefit calculations
• Budget category totals and grand total calculations
• Required fields for each personnel line

What Research.gov Does NOT Enforce

• The two-month salary cap across multiple proposals (you must track this yourself)
• Participant support cost protections (the system lets you enter them, but doesn't prevent misclassification)
• Equipment threshold compliance (you classify items yourself)
• Subaward F&A base calculations (you and your SPO verify this)

Tips for Using the Budget Module

Enter each year separately. Research.gov has tabs for each budget year. Don't just divide the total by the number of years; account for salary increases (typically 3% per year), inflation on supplies, and changes in personnel over the project period.

Budget justification is a separate document. You write the justification as a PDF upload, not in the budget module. Every line item needs a justification sentence or paragraph. Reviewers read this document, and vague justifications ("supplies for the project") trigger questions.

Build the budget before writing the project description. Your 15-page project description should match your budget. If you budget for three graduate students but only describe work for two, reviewers will notice.

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Typical NSF Budget Sizes by Program

Different NSF programs have different budget norms. Submitting a $1 million in FY2025 budget to a program that typically funds $300,000 awards signals that you haven't done your homework.

Check the program solicitation for budget guidance. Most solicitations specify a budget range or cap. If the solicitation says "up to $500,000 total," don't request $499,999 unless you can justify every dollar. Program officers notice when budgets are padded to hit the maximum.

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The Budget Justification: What Reviewers Actually Read

The budget justification is a narrative document that explains every line item in your budget. Reviewers read it. Program officers read it. Compliance staff read it. Here's how to write it well.

Structure

Organize the justification to mirror the budget categories:

1. Senior Personnel: Name, role, months of effort, monthly rate, total salary. Justify the level of effort: "The PI will devote 1.5 months of summer salary to this project, managing graduate students, analyzing data, and preparing manuscripts."
2. Other Personnel: Same format. For graduate students, explain their role: "One graduate student (12 months/year for 3 years) will conduct the experiments described in Tasks 1-3 and write their dissertation on this topic."
3. Fringe Benefits: State the institutional rate for each personnel category: "Fringe benefits are calculated at 28% for faculty and 10% for graduate students, based on the university's approved rate agreement."
4. Equipment: Name each item, provide cost, and explain why it's needed: "Confocal microscope (Zeiss LSM 900, $125,000): required for the fluorescence imaging described in Task 2. No comparable instrument is available on campus."
5. Travel: Itemize trips: "Two domestic conference trips ($2,500 each): PI will present results at the annual ACS meeting and the Gordon Conference on Polymer Physics."
6. Participant Support: Detail the activity, number of participants, and per-participant costs: "Summer workshop for 15 undergraduate students: $1,500 stipend + $500 travel per student = $30,000 total."
7. Other Direct Costs: Itemize supplies, subawards, publication costs, computing, etc.
8. Indirect Costs: State the negotiated rate and MTDC base.

What Gets Flagged

• Round numbers with no justification ("$50,000 for supplies")
• Personnel effort that doesn't match the project description
• Equipment that could be available through shared facilities
• Travel to conferences unrelated to the project
• Consultant rates without a justification of the daily rate

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What the PAPPG Doesn't Tell You About NSF Budget Preparation

The Proposal and Award Policies and Procedures Guide covers the rules, but there are practical realities you learn from experience.

Program officers negotiate budgets. If your proposal is selected for funding but the budget is higher than the program can accommodate, the program officer will contact you to negotiate cuts. Know in advance which items you'd cut if asked to reduce by 10% or 20%. Having a prioritized list speeds up the negotiation and gets your award processed faster.

Reviewers judge budgets informally. The panel's formal evaluation focuses on the science, but reviewers notice if a budget seems high for the proposed work. A $600,000 budget for a project that could be done for $400,000 makes the PI look either naive or greedy. Budget what you need, not what the program allows.

The two-month rule creates real strategic constraints. If you're building a career with multiple NSF grants, you'll hit the two-month cap fast. Some experienced PIs list zero salary on new proposals and fund their effort through other sources, reserving their NSF salary allocation for a large center grant or CAREER award. This is a strategic choice, but it requires institutional salary support.

Fringe rate changes mid-project. Your institution's fringe rates are renegotiated periodically, sometimes mid-award. Build a small contingency into personnel costs (an extra 1-2% inflation per year) to absorb rate changes. NSF allows reasonable annual increases.

Subaward budgets are where compliance problems hide. Your collaborator's institution may have different rules, different F&A rates, and different fringe rates. Get the subaward budget and justification from your collaborator early, not the week before the deadline. Your SPO needs time to verify the numbers.

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Common NSF Budget Mistakes and How to Avoid Them

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Building Your NSF Budget: Step-by-Step

1. Read the solicitation for budget limits, special rules, and any program-specific restrictions.
2. Get current rates from your SPO: fringe rates, F&A rate, graduate student stipends, tuition rates.
3. Calculate personnel costs for each year, with annual escalation.
4. List equipment and get quotes if over $25,000.
5. Estimate travel with specific conferences and field trips named.
6. Identify participant support activities and calculate per-participant costs.
7. Request subaward budgets from collaborators (give them at least 4 weeks).
8. Calculate indirect costs on the correct MTDC base.
9. Write the budget justification in parallel with the project description.
10. Have your SPO review the budget at least 2 weeks before the deadline.

Understanding how NSF grant review works helps you write a budget that reviewers won't question. And knowing the overall NSF grants ecosystem helps you target the right program with the right budget size.

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Sources

• NSF Proposal and Award Policies and Procedures Guide (PAPPG), Chapter II.D (Budget): https://www.nsf.gov/publications/pub_summ.jsp?ods_key=pappg (opens in a new tab)
• Research.gov Proposal Preparation and Submission: https://www.research.gov/ (opens in a new tab)
• NSF Award Conditions (Financial Requirements): https://www.nsf.gov/awards/managing/award_conditions.jsp (opens in a new tab)
• GSA Per Diem Rates: https://www.gsa.gov/travel/plan-book/per-diem-rates (opens in a new tab)
• 2 CFR 200 (Uniform Guidance for Federal Awards): https://www.ecfr.gov/current/title-2/subtitle-A/chapter-II/part-200 (opens in a new tab)