Is it real?
Yes. Never revoked by the IRS. Latest filing on record: FY2025. IRS ruling in May 2013.
IRS Pub. 78 · IRS Auto-Revocation List · IRS Business Master File
Where the money goes
99 cents of each dollar spent went to programs.
Form 990 Part IX, line 25, columns B–D. Every line is in By the numbers.
Something off? Claim to fix it
Who runs it and what they're paid
5 people listed on the 990; $49K paid to officers and key staff.
Sarah-Marie Belcastro PHD’s $46K as President and Chair of the Board is at the 37th percentile of top reported officer pay among 1613 $100K–1M education nonprofits. Peer set: organizations in the same NTEE major field of work and revenue-size band, compared on each org’s own highest-paid officer/key-employee, from Form 990 Part VII / 990-PF Part VIII. Descriptive placement, not a verdict on whether the pay is appropriate.
Compensation history total reportable pay by year · 3 named individuals · Part VII
| Name | FY2025 | FY2024 | FY2023 | FY2022 | FY2021 | FY2020 |
|---|---|---|---|---|---|---|
| Sarah-Marie Belcastro PHD | $45,983 | $49,140 | $44,098 | $39,114 | $35,596 | $29,648 |
| Hannah Alpert PHD | $3,337 | — | — | $4,328 | $4,244 | $5,530 |
| Emily Peters PHD | — | — | $3,049 | — | $472 | $943 |
Total reportable compensation (Form 990 Part VII column D / Schedule J column E) by filing year, matched by name within this organization. The Schedule J base / bonus / deferred breakdown is not parsed into this dataset.
See Mathematical Staircase executive salaries →On this list? Claim this org
Something off? Claim to fix it
Questions the 990 asks
The form asks each of these directly. These are the filed answers.
- Family or business ties among officersPt VI · Ln 2Yes
- Top official's pay set by an independent reviewPt VI · Ln 15aNo
Programs and updates
Teaches talented students mathematical thinking and writing through summer programs.
Questions for Mathematical Staircase
Your first name shows with your question. Mathematical Staircase answers here, for everyone.
Know this org? Add your story
Mathily
a residential summer program for mathematically gifted high-school students. Number of students enrolled was 46 in a 5-week program of courses, presentations and leisure activities. Fifteen trainees (staff members) also benefitted.
Mathily-Er
Similar to MathILy with slightly younger students and who are earlier in their mathematical development. Number of students enrolled was 32 in a 5-week program of courses, presentations and leisure activities. Eleven trainees (staff members) also benefitted.
Mathily-Est
A Research Experience for Undergraduates (REU) focused on beginning college students. Number of students enrolled was 4 in an 8-week program focused on a program of research, presentations, interactions with the MathILy students and leisure activities.
Funders
Who pays for it.
From grant filings on record. Receipts are incomplete: individual donors are never listed.
Grants
By the numbers
The FY2025 990, line by line.
Download 990
| Line | Start FY25 | End FY25 |
|---|---|---|
| Cash and savingsLn 1–2 | $345K | $359K |
| InvestmentsLn 11–13 | $0 | $0 |
| Total assetsLn 16 | $345K | $359K |
| LiabilitiesLn 26 | $10K | $4K |
| Net assetsLn 32 | $336K | $355K |
| Line | Total | Programs | Management | Fundraising |
|---|---|---|---|---|
| Grants to domestic organizationsLn 1 | $0 | $0 | ||
| Grants to domestic individualsLn 2 | $0 | $0 | ||
| Grants and assistance to foreign recipientsLn 3 | $0 | $0 | ||
| Benefits paid to or for membersLn 4 | $0 | $0 | ||
| Pay of current officers, directors and key staffLn 5 | $49K | $49K | $0 | $0 |
| Pay of disqualified personsLn 6 | $0 | $0 | $0 | $0 |
| Other salaries and wagesLn 7 | $25K | $25K | $0 | $0 |
| Pension plan contributionsLn 8 | $0 | $0 | $0 | $0 |
| Other employee benefitsLn 9 | $0 | $0 | $0 | $0 |
| Payroll taxesLn 10 | $5K | $5K | ||
| Management feesLn 11a | $0 | $0 | $0 | $0 |
| Legal feesLn 11b | $0 | $0 | $0 | $0 |
| Accounting feesLn 11c | $2K | $0 | $2K | $0 |
| Lobbying feesLn 11d | $0 | $0 | $0 | $0 |
| Professional fundraising feesLn 11e | $0 | $0 | ||
| Investment management feesLn 11f | $0 | $0 | $0 | $0 |
| Other fees for servicesLn 11g | $0 | $0 | $0 | $0 |
| Advertising and promotionLn 12 | $319 | $319 | $0 | $0 |
| Office expensesLn 13 | $11K | $10K | $1K | |
| Information technologyLn 14 | $0 | $0 | $0 | $0 |
| RoyaltiesLn 15 | $0 | $0 | $0 | $0 |
| OccupancyLn 16 | $0 | $0 | $0 | $0 |
| TravelLn 17 | $16K | $16K | $0 | $0 |
| Travel and entertainment for public officialsLn 18 | $0 | $0 | $0 | $0 |
| Conferences, conventions and meetingsLn 19 | $0 | $0 | $0 | $0 |
| InterestLn 20 | $0 | $0 | $0 | $0 |
| Payments to affiliatesLn 21 | $0 | $0 | $0 | $0 |
| Depreciation, depletion and amortizationLn 22 | $0 | $0 | $0 | $0 |
| InsuranceLn 23 | $7K | $7K | ||
| Other expenses (24a–d)Ln 24 | $384K | $384K | $0 | $0 |
| Total functional expensesLn 25 | $500K | $497K | $3K | $0 |
Filing history
| Year | Money in | Money out | In minus out | Net assets | Download |
|---|---|---|---|---|---|
| FY2025 Latest Viewing | $519K | $500K | $19K | $355K | 990 PDF |
| FY2024 | $625K | $532K | $94K | $336K | 990 PDF |
| FY2023 | $547K | $511K | $36K | $240K | 990 PDF |
| FY2022 | $495K | $524K | −$29K | $196K | 990 PDF |
| FY2021 | $223K | $152K | $71K | $225K | 990 PDF |
| FY2020 | $217K | $150K | $67K | $155K | 990 PDF |
More to add? Claim this org
Schedules filed Part IV
See the full FY2025 990 (6 parts)
Part I · Summary $519,331 revenue, 12 lines filed
Part VI · Governance 3 of 5 board members independent, 2 to look at
Part VIII · Statement of revenue $519,331 across 12 lines filed
Part IX · Statement of functional expenses $500,146 across 30 lines filed
Part X · Balance sheet $359,208 assets, 22 lines filed
Part XI · Reconciliation of net assets $355,094 net assets at year end
Form 990 e-file (XML) FY2025 from the IRS · Classification, formation year and address from the IRS Business Master File
Similar organizations you could support · Compare with another nonprofit
Names, privacy, and removal requests More
The names, titles, and compensation shown on this page are reproduced from IRS Form 990 filings, which are public records.
Philanthropy.org does not alter the content of those filings. All information appears exactly as reported by the filing organization for the tax year shown.
We publish only information contained in the public IRS filing — and less than the filing contains. Our profile pages do not display street addresses, telephone numbers, personal email addresses, or other personal contact information, even where the filing includes them.
Many people share the same name. A name shown on this page reflects only what one organization reported in one IRS filing for one tax year. It should not be interpreted as identifying any other individual with the same or a similar name.
If you are no longer affiliated with the organization, your name will generally stop appearing in future IRS filings once the organization no longer reports you. Pages for tax years in which you were reported remain published because those filings remain part of the public record.
Philanthropy.org does not alter or remove IRS filing records. Removing a page from this website would not remove the underlying IRS filing, which remains publicly available from the IRS and other publishers of the same information.
If you believe the IRS filing itself is inaccurate, corrections must be made by the filing organization or the IRS directly.
Your org? Add context
Made it to the end? Claim this org