Data sources
Most GlenCalc calculators use only math and fixed definitions. A few depend on figures that change: tax brackets, platform fees, exchange rates and inflation. Each lives in a data file with its official source and the date it was last checked. The site refuses to build if any of them is older than its limit, so an out-of-date figure can’t go live quietly.
US federal income, payroll, estate and gift tax figures for 2026
Checked October 31, 2026; in effect from January 1, 2026. Checked by hand each month; the site won’t build if it is more than 400 days old.
- IRS Revenue Procedure 2025-32 (2026 inflation adjustments), sections 4.01 and 4.15: “Unmarried Individuals (other than Surviving Spouses and Heads of Households) ... $16,100”
- IRS IR-2025-103: inflation adjustments for tax year 2026: “For single taxpayers and married individuals filing separately, the standard deduction rises to $16,100 for tax year 2026”
- IRS Publication 15 (2026) and Topic 751: Social Security wage base and rates: “For earnings in 2026, this base limit is $184,500.”
- IRS Topic 560: Additional Medicare Tax
IRS Uniform Lifetime Table (Publication 590-B, Table III) and RMD starting ages
Checked October 31, 2026; in effect from January 1, 2022. Checked by hand each month; the site won’t build if it is more than 400 days old.
- IRS Publication 590-B (2025), Appendix B, Table III: “Age 73 for tax years 2023 and later.”
- SECURE 2.0 Act of 2022, section 107 (applicable age 73, then 75 for those turning 74 after 2032)
US seller and payment platform fees
Checked October 31, 2026; in effect from October 31, 2026. Checked by hand each month; the site won’t build if it is more than 45 days old.
- Etsy Help: fees and taxes for selling; payment processing fees: “6.5% of the total order amount in your designated listing currency.”
- eBay: selling fees: “13.6% on total amount of the sale up to $7,500 calculated per item”
- PayPal: business fees (last updated October 1, 2026)
- Stripe: pricing: “2.9% + 30¢ per successful transaction for domestic cards”
- Square: our fees: “Tap, dip, or swipe: 2.6% + 15¢”
- Shopify: pricing (plan comparison)
- Amazon: selling plans and referral fees
US CPI-U, all items, US city average (1982–84 = 100)
Checked November 1, 2026; in effect from September 1, 2026. Updated automatically; the site won’t build if it is more than 75 days old.
ECB euro foreign exchange reference rates
Checked November 1, 2026; in effect from October 30, 2026. Updated automatically; the site won’t build if it is more than 10 days old.