Updated May 26, 2026 — calculators reflect IRS Rev. Proc. 2025-32 and OBBBA bracket extensions for tax year 2026.Methodology · Changelog · Editorial policy
CalcYetUS Payroll & Tax Research
Sources

The resources we actually open

Every CalcYet calculation and every editorial article traces back to a primary source. These are the actual URLs the editorial team works against — not a generic “tax resources” index stuffed for SEO. Organized roughly by how often we open each one.

Worth knowing
IRS site search is unreliable enough that we keep the underlying URLs bookmarked. If you find yourself searching irs.gov for the same publication a third time, save the URL. The publications themselves rarely move; the search index regenerates often.

The IRS resources we open every week

About 90% of our citations trace back to a handful of pages on IRS.gov. The IRS site search is famously bad, so we keep the URLs bookmarked. Here are the ones we actually use, in rough order of how often we open them.

Publication 15-T — Federal Income Tax Withholding Methods
The withholding tables your employer’s payroll system implements. Updated each January for the new tax year. If our W-4 calculator disagrees with your paystub by more than a few dollars, this is the document to check first.
Publication 17 — Your Federal Income Tax
The IRS’s general guide for individual filers. About 300 pages. We treat it as the authoritative plain-language reference for everything that doesn’t have a dedicated publication.
IRS Tax Withholding Estimator
The IRS’s own withholding calculator. Slower than ours and more thorough on multi-job households. If you owe a lot in April, run yours and ours and reconcile the difference.
Form W-4 — Employee’s Withholding Certificate
The form you give your employer. The 2020 redesign removed allowances. Most-missed field: the Step 2(c) Multiple Jobs box.
Form 1040-ES — Estimated Tax for Individuals
Quarterly estimated payment voucher plus the worksheet. The four due dates and the safe-harbor math are on the first page of the instructions.
Publication 505 — Tax Withholding and Estimated Tax
The IRS’s deeper treatment of withholding and estimated payments. Includes worksheets for the annualized installment method and safe-harbor computations.
Publication 969 — Health Savings Accounts and Other Tax-Favored Plans
HSAs, FSAs, MSAs, HRAs. The HSA section in particular is the source for the “reimburse yourself from a 20-year-old receipt” rule (Notice 2004-2 Q&A 39 is referenced here).
Publication 15-B — Employer’s Tax Guide to Fringe Benefits
Where to look up which fringe benefits are excludable from income and which are imputed. The group-term-life-over-$50k rule lives here.
Publication 560 — Retirement Plans for Small Business
SEP-IRA, SIMPLE IRA, and qualified plans for self-employed and small-business owners. Includes the contribution-limit tables.
Publication 970 — Tax Benefits for Education
American Opportunity Credit, Lifetime Learning Credit, 529 plans, Coverdell, student loan interest deduction. The no-double-dipping rule for AOTC and 529 is here.
IRS Newsroom — 2026 Tax Year Inflation Adjustments
The annual release summarizing inflation-adjusted dollar figures. The full numbers are in Revenue Procedure 2025-32, but the Newsroom release is the readable summary.
IRS — Cost-of-Living Adjustments for Retirement Items
The 401(k), 403(b), 457(b), SEP, SIMPLE, traditional IRA, Roth IRA limits in one table. Updated each fall.
IRS Payments Center
Direct Pay (free, no account), debit/credit card processors, EFTPS enrollment, IRS Online Account access. Where to actually send your quarterly estimated payment.
IRS — Credits and Deductions for Individuals
The index of every individual credit and deduction. Useful as a checklist to make sure you didn’t miss one (the Saver’s Credit, the Residential Clean Energy Credit, the Energy Efficient Home Improvement Credit are the most-missed in our experience).

Social Security & Medicare

FICA-related figures come from the Social Security Administration, not the IRS, even though FICA tax is collected by the IRS. The cleanest annual reference is the SSA fact sheet released each October.

SSA — Contribution and Benefit Base (historical)
The Social Security wage base from 1937 through the current year. 2026 is $176,100. The methodology under Section 230 of the Social Security Act explains why it doesn’t always rise.
SSA — 2026 Fact Sheet (Cost-of-Living Adjustment)
The one-page fact sheet released each October that summarizes the next year’s wage base, COLA, earnings test, and Medicare premium changes.
my Social Security account
Your earnings record on file with SSA. Worth pulling every few years to confirm your Box 3 wages were reported correctly — this is what determines your eventual benefit.
IRS Topic 751 — Social Security and Medicare Withholding Rates
The IRS’s short reference for the OASDI and HI rates and thresholds.
IRS — Additional Medicare Tax FAQ
Covers the 0.9% Medicare surtax on wages above $200,000 single / $250,000 MFJ. The employer-withholding rule and the filing-status reconciliation are explained here.

Department of Labor (FLSA, overtime, payday)

Wage-and-hour issues — overtime, minimum wage, payday timing, recordkeeping — are under the Department of Labor, not the IRS. The Wage and Hour Division is the operational arm.

DOL Wage and Hour Division — Overtime Pay
The Fair Labor Standards Act overtime rules: 1.5x after 40 hours in a workweek for non-exempt employees. Also covers the executive, administrative, professional, and computer-employee exemptions.
DOL — State Minimum Wage Map
Each state’s current minimum wage compared to the federal $7.25. Updated whenever a state changes its rate.
DOL — State Payday Requirements
Each state’s rules on pay frequency (weekly, biweekly, semimonthly, monthly), final pay timing on separation, and recordkeeping. Texas and Tennessee are notable for the least-prescriptive rules.
DOL — Fair Labor Standards Act
The full FLSA hub. Covers minimum wage, overtime, child labor, recordkeeping, and tipped-employee rules.
DOL — Employee Benefits Security Administration
The federal regulator for ERISA, 401(k) plans, group health coverage, and retirement protections. Where to file a complaint about a 401(k) match that didn’t vest or a COBRA election that didn’t process.

State revenue agencies

Every state with an income tax maintains a Department of Revenue or equivalent agency. Their withholding tables and state-specific W-4 forms are authoritative for that state.

IRS directory — State Government Tax Agencies
The IRS’s curated list of every state’s tax authority. The cleanest single jumping-off point when you need to find a state-specific form.
California — Franchise Tax Board
California’s 30/40/0/30 quarterly schedule, the DE-4 form, the SDI rate, and the SB 951 mental health surcharge details all live here.
New York — Department of Taxation and Finance
Form IT-2104 (NY state W-4 equivalent), the IT-2105 estimated payment voucher, and the convenience-of-employer regulation TSB-M-06(5)I.
Illinois — Department of Revenue
MyTax Illinois portal, IL-W-4, and the flat 4.95% Illinois income tax. Note: Illinois has no local income tax even though Chicago has a head tax (employer-side, not employee-side).
Pennsylvania — Department of Revenue
Pennsylvania’s flat 3.07% state tax, the unusual rule that 401(k) contributions are taxable at the state level, and the REV-419 reciprocity certificate.
Michigan — Department of Treasury
Michigan’s 4.05% state tax, Detroit’s 2.4% city tax, and the MI-W4 form.

Third-party references worth knowing

We don’t treat third-party publishers as primary sources, but several reference sites do an excellent job of summarizing state-level rules and historical changes. These are the ones we actually use as cross-checks.

Tax Foundation
Right-leaning policy think tank with the best US state-tax rate maps and historical bracket data. The annual State Business Tax Climate Index is the most-cited state-comparison source in serious tax journalism.
Institute on Taxation and Economic Policy (ITEP)
Left-leaning policy organization. Their Who Pays? series is the standard reference for incidence analysis.
Congressional Research Service Reports
Non-partisan staff research for Congress, publicly accessible. Excellent backgrounders on every major tax provision. Search for the CRS report number when a topic comes up in legislative debate.
Joint Committee on Taxation
The official congressional committee that scores tax legislation. Their score sheets explain what a proposed bill actually does in revenue terms.
AICPA & CIMA
Professional association for US CPAs. Their tax section maintains practice guides on multistate tax, partnership tax, and specialty topics. Members-only for most of the deep material.
National Association of Enrolled Agents (NAEA)
Professional association for IRS Enrolled Agents. Useful for finding a credentialed practitioner near you.

Tools we recommend (and don’t)

We are not affiliated with any of these. Mentions are not endorsements; they are honest opinions from people who’ve used them.

FreeTaxUSA
Federal filing is free; state is a small flat fee. Honest, no-upsell software. The user interface is dated but the tax computation engine is solid. The pick for most W-2 filers who don’t want to pay TurboTax pricing.
IRS Free File
Free federal filing through partner software if your AGI is under the threshold (about $79,000 for tax year 2024 returns, adjusted annually).
IRS Free File Fillable Forms
The actual federal forms in a fillable-PDF-equivalent web interface. No software guidance. Free for any income level. Best for people who already know what they’re doing.
Consumer Reports — Tax Software Reviews
Annual independent review. The only tax-software round-up that isn’t obviously affiliate-driven. Behind a paywall but worth the $20 a year if you’re shopping software seriously.

What about social media tax content?

We don’t link to TikTok or YouTube tax content for a reason: most of it is wrong. The “tax-saving hacks” that get traction in short-form video usually fail at least one of three tests — they confuse marginal and effective rates, they ignore phase-outs, or they describe a provision that doesn’t exist in the way the creator says it does. If you see a tax tip on social media that sounds too good, check it against the actual IRS publication. Nine times out of ten the answer is more boring and less generous than the video claimed.

That said, a small number of credentialed practitioners do post real, sourced tax content on professional platforms. CPAs and Enrolled Agents who name themselves, link to their state license registry, and cite the IRC section they’re explaining are usually reliable. The unnamed accounts with stock-photo avatars and the “watch this before April 15” framing are almost universally not.

Suggest a resource

We add to this page whenever a reader points out a primary source we missed. Send the URL and a sentence about what it’s for to contact@calcyet.com. We don’t accept paid placements; the page is editorial.