PaycheckMath

What PaycheckMath is for

"What's my take-home pay on $4,000 biweekly", "when does my paycheck get bigger because Social Security caps out", "what's the Additional Medicare Tax on a $220k salary", "federal withholding on a $90,000 salary paid semimonthly, married filing jointly" — the gross-to-net questions people ask before payday. PaycheckMath answers them with real arithmetic over published, dated IRS and SSA figures — no upstream calls, no accounts, nothing stored.

What it does

Federal withholding. A simplified annualized-percentage-method estimate: annualize this period's taxable wages (after any pre-tax 401(k) or health premium), subtract the annual standard deduction, tax the result at the current-year annual brackets, divide by pay periods. This is explicitly not the IRS Publication 15-T wage-bracket table an employer's payroll system actually uses — that table encodes Form W-4 elections (multiple jobs, dependents, extra withholding) this tool does not ask for — but it is real, correct bracket math, clearly labeled as an approximation.

FICA, wage-base aware. Social Security at 6.2% up to the annual wage base ($176,100 in 2025, $184,500 in 2026), Medicare at 1.45% with no cap, and the Additional Medicare Tax — an extra 0.9% that employers must withhold once an employee's wages from them alone exceed $200,000 in the year, regardless of filing status. Given a year-to-date wage figure, the calculator correctly stops charging Social Security once the wage base is reached partway through the year, and flags the (real) gap between that flat $200,000 employer-withholding trigger and the employee's actual filing-status liability threshold, which is reconciled at filing on Form 8959.

Full paycheck. Combines withholding and FICA into one gross-to-net breakdown, correctly modeling that a traditional 401(k) contribution reduces federal taxable wages but not FICA wages, while a Section 125 cafeteria-plan health premium reduces both. State and local income tax are never estimated — they vary too much by state (nine states charge none on wages; others range roughly 3–13%) to guess responsibly — the result instead flags where to look.

Full-year projection. Runs the same paycheck across every pay period in the year and returns a schedule plus annual totals, including exactly which pay period the Social Security wage base is reached (after which take-home pay rises for the rest of the year on that income).

Glossary. Plain-language definitions: FICA, Social Security wage base, Additional Medicare Tax, pre-tax deduction, Section 125 cafeteria plan, Form W-4, percentage method, supplemental wages, pay frequency.

What it is not

Not personalized tax or financial advice, and not a substitute for your actual pay stub, your employer's payroll system, or a tax professional. It does not model your Form W-4, state or local tax, post-tax deductions, bonuses/supplemental wages, or employer-specific plan rules. Supported for tax years 2025 and 2026 only — the tables need updating when the IRS or SSA publishes new figures for a later year.

Built and maintained by Unify Dynamics LLC. Contact: agent@connectorbay.com.

PaycheckMath — Privacy Policy

Effective 28 September 2026. Unify Dynamics LLC ("we", "us"), Menlo Park, California.

What PaycheckMath is. PaycheckMath is a connector (an MCP server and REST API) that AI assistants and personal agents call on your behalf for US gross-to-net paycheck calculations: federal withholding estimates, FICA (Social Security, Medicare, Additional Medicare Tax), and full paycheck/annual projections. You interact with your assistant; the assistant sends us only the numbers needed for that one calculation.

What we receive. The arguments of each tool call — a gross pay amount, pay frequency, filing status, pre-tax contribution percentages or dollar amounts, a year-to-date wage figure, and a tax year — the technical headers needed to serve the request (an IP address or a client identifier supplied by the assistant, and a Pro API key if you have one), and standard server logs.

Everything is computed on our server and nothing is stored. Every calculation uses bundled, dated IRS/SSA rate tables and standard published formulas computed from the numbers you provide; no request is forwarded to any third party, and no query — including any wage, salary, or deduction figure you enter — is logged in request bodies, recorded, or used to train anything.

What we do not receive or store. We do not receive your conversation with the assistant, your name, Social Security number, employer name, bank or payroll account information, or any other identifying information, and we do not build a financial profile from your queries: each calculation is answered independently and nothing carries over between requests. Rate-limit counters (a client identifier and timestamps) are held in memory for at most 24 hours. Hosting-provider access logs, which contain IP addresses and request paths but not request bodies, are retained for up to 30 days for security and abuse prevention.

Sub-processors. None — every tool is computed locally. Hosting: Vercel (United States regions).

Legal bases and your rights. For users in California, the EU/UK and elsewhere, our processing is necessary to provide the service you request through your assistant. Because we store no personal data beyond short-lived logs, requests to access, correct or delete personal data are usually satisfied automatically; you can still contact agent@connectorbay.com and we will respond within 30 days. We do not sell or share personal information and do not use your data to train models.

Children. PaycheckMath is a general-audience service for adults; we knowingly collect no personal data from anyone.

Changes. We will post changes here with a new effective date.

PaycheckMath — Terms of Service

Effective 28 September 2026. These terms govern use of the PaycheckMath connector ("the Service") operated by Unify Dynamics LLC ("we", "us").

1. The Service. PaycheckMath returns US gross-to-net paycheck calculations — simplified federal withholding estimates, FICA (Social Security, Medicare, Additional Medicare Tax), full paycheck breakdowns, and full-year projections — computed from bundled, dated IRS/SSA rate tables and the numbers you provide. It is accessed through an AI assistant or directly over MCP or HTTP.
2. Not tax or financial advice. PaycheckMath's calculations are general educational information and illustrative estimates based on rates you supply or that are bundled from published government tables — not a recommendation, and not individualized tax, payroll, or financial advice. Consult a tax professional, your payroll department, or your actual pay stub for figures you rely on.
3. Federal withholding is simplified, not the official method. federal_withholding_estimate and any tool that uses it approximate the IRS's annualized percentage method but do not model Form W-4 elections (multiple jobs, dependents, extra withholding) and are not the IRS Publication 15-T wage-bracket table your actual employer uses — real withholding will differ.
4. State and local tax are never estimated. These figures vary too much by jurisdiction to guess responsibly; the Service flags this rather than returning a number.
5. Rates and rules change. Standard deductions, tax brackets, the Social Security wage base, and FICA thresholds are supported for tax years 2025 and 2026 as published by the IRS and SSA at build time; the government revises several of these figures annually. Always check irs.gov or ssa.gov before relying on a figure for a filing or a decision.
6. Estimates, not guarantees. Actual payroll withholding varies by employer, benefits elections, and individual circumstances; nothing in the Service guarantees any particular paycheck outcome.
7. Acceptable use. Automated use within the published rate limits is welcome.
8. Availability. The Service is provided "as is" without warranty. We may change, limit or discontinue it at any time.
9. Data. Our Privacy Policy describes what we process. In short: your query is answered on our server and nothing is stored.
10. Attribution. Internal Revenue Service (IRS); Social Security Administration (SSA).
11. Pro keys. Optional Pro API keys are issued at our discretion, are personal to the holder and may be revoked for abuse.
12. Liability. To the fullest extent permitted by law, Unify Dynamics LLC is not liable for any financial loss arising from use of or reliance on the Service. Our total liability is limited to US $100.
13. Governing law. California law; venue in San Mateo County, California.
14. Contact. Unify Dynamics LLC · agent@connectorbay.com · https://connectorbay.com/paycheckmath

PaycheckMath support

Email agent@connectorbay.com. We answer within two business days.

• MCP endpoint: https://paycheckmath.connectorbay.com/mcp
• REST API: https://paycheckmath.connectorbay.com/openapi.json
• Live status: https://paycheckmath.connectorbay.com/health

When you report a problem, include the question you asked your agent, roughly when, and which agent you used (for example Claude, ChatGPT or Gemini). Never send us passwords, account numbers or ID numbers. PaycheckMath never asks for them.