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IRS-authorized e-file provider · not the IRS

Nonprofit · EIN 83-2486423

INTERNATIONAL SLIDE RULE MUSEUM

Also known as ISRM

Tax-exempt · LOUISVILLE, CO 80027

Address and contacts

Address (IRS master file)
1944 QUAIL CIR, LOUISVILLE, CO 80027-1188
In care of
% MICHAEL KONSHAK
Mailing address (990-N for 2025)
1944 Quail Circle, Louisville CO 80027
Principal officer (990-N for 2025)
Michael V Konshak, 1944 Quail Circle, Louisville CO 80027

What it must file and when

IRS records say it files Form 990-N (e-Postcard). Gross receipts normally $50,000 or less. Its accounting year ends in December, so each return is due on the 15th day of the 5th month after that.

Tax yearYear endedDueIRS public records
2025December 31, 2025May 15, 2026990-N on file
2024December 31, 2024May 15, 2025990-N on file
2023December 31, 2023May 15, 2024990-N on file

File the 2026 990-N for INTERNATIONAL SLIDE RULE MUSEUM

Due May 17, 2027 · e-filed with the IRS by 990.tax, an IRS-authorized e-file provider

IRS record

EIN
83-2486423
Tax-exempt status
501(c)(3): Charitable, religious, educational or scientific organization
Foundation status
Publicly supported organization (509(a)(2))
Donations deductible (Pub 78)
Public charity, 50% deduction limit
Exempt since
2018
Accounting year ends
December
Files
Form 990-N (e-Postcard)

Filing history

FormYear endedRevenueExpensesAssetsReturn
990-N for 2025
Officer: Michael V Konshak
December 31, 2025≤ $50,000 receipts––e-Postcard
990-N for 2024
Officer: Michael Vaughn Konshak
December 31, 2024≤ $50,000 receipts––e-Postcard
990-N for 2023
Officer: Michael Konshak
December 31, 2023≤ $50,000 receipts––e-Postcard
990-N for 2022
Officer: Michael Konshak
December 31, 2022≤ $50,000 receipts––e-Postcard
990-N for 2020
Officer: Michael Konshak
December 31, 2020≤ $50,000 receipts––e-Postcard
990-N for 2019
Officer: Michael Konshak
December 31, 2019≤ $50,000 receipts––e-Postcard

990-N: the IRS bulk file holds only the latest e-Postcard per organization; earlier years come from archived copies of that file since 2020 and can have gaps (the IRS e-Postcard search lists every one). 990, 990-EZ, 990-PF, 990-T: every e-filed return in the IRS e-file index since 2019; XML for the latest three processing years, amounts from the IRS Statistics of Income extracts before that. PDF copies and determination letters at the IRS (search EIN 83-2486423).

Questions about INTERNATIONAL SLIDE RULE MUSEUM

What is the EIN of INTERNATIONAL SLIDE RULE MUSEUM?
The employer identification number (EIN) of INTERNATIONAL SLIDE RULE MUSEUM is 83-2486423.
Is INTERNATIONAL SLIDE RULE MUSEUM tax-exempt?
Yes. The IRS lists it as tax-exempt under section 501(c)(3) since 2018.
Are donations to INTERNATIONAL SLIDE RULE MUSEUM tax-deductible?
Yes. It is listed in IRS Publication 78 (Public charity, 50% deduction limit).
Which annual return does INTERNATIONAL SLIDE RULE MUSEUM file?
Form 990-N (e-Postcard). Gross receipts normally $50,000 or less.
When is the next return of INTERNATIONAL SLIDE RULE MUSEUM due?
The return for tax year 2026 (the year ending December 31, 2026) is due May 17, 2027. Form 8868 extends it by six months; the 990-N cannot be extended.
When did INTERNATIONAL SLIDE RULE MUSEUM last file with the IRS?
The latest return in the IRS public files is the 990-N for 2025 for the year ended December 31, 2025.
Who is the principal officer of INTERNATIONAL SLIDE RULE MUSEUM?
The 990-N for 2025 names Michael V Konshak.

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