# Workforce

> How payroll and HR run in software, from gross-to-net and payroll tax at every level to garnishments, wage-hour law, benefits, contractors and global pay.

A paycheck looks like one number, and underneath it is a calculation and a set of promises. Hours, rates and elections become gross pay; gross pay becomes federal, state and local taxes, benefit deductions and garnishments, each with its own taxable wage base; and what's left moves to the employee's bank on a date the law fixes, while every amount withheld becomes a liability owed to an agency, a carrier, a plan or a court on its own deadline. A payroll provider, a PEO, an employer of record and an embedded payroll API are all keeping those promises for someone else's employees, out of money they collected first. This book surveys how the industry does each piece, benchmarked across ADP, Paychex, Paycom, Paylocity, Dayforce, Workday, Gusto, Rippling, Deel, TriNet, Check and the others, with no single company as the model, and how you'd build it, extending one core data model chapter by chapter.

It reads in ten parts, plus a glossary: the business (providers, revenue, agents and PEOs), gross to net (withholding, deductions, tips and corrections), payroll tax at every level, moving the money (funding, client funds, direct deposit, child support and garnishments), time and wage-hour law, hiring and HR records, leave, benefits administration, contractors and global payroll, and running the platform (embedded payroll, unified APIs, architecture, controls and fraud).

## Chapters

- [The Workforce Business](https://www.syntaqx.com/books/workforce/workforce-business): How payroll providers, PEOs, EORs and HR systems pay people: the parties, the money, the life of a pay run, a tax dollar and a hire, and the data model.
- [The Payroll & HR Landscape](https://www.syntaqx.com/books/workforce/workforce-landscape): Payroll and HR providers by clients, workers paid and revenue from filings, private players by what they publish, the segments, consolidation and switching.
- [How Payroll Providers Make Money](https://www.syntaqx.com/books/workforce/revenue-models): Per employee pricing, interest on client funds from 10-Ks, rate sensitivity, PEO gross billings and net revenue, insurance margins, EOR and embedded fees.
- [Who Runs Payroll: Agents & Liability](https://www.syntaqx.com/books/workforce/who-runs-payroll): In-house, payroll service providers, reporting agents, Section 3504 agents, CPEOs, ASOs and EORs: who files under which EIN, who stays liable, and EFTPS.
- [PEOs & Co-Employment](https://www.syntaqx.com/books/workforce/peos-and-co-employment): The client service agreement, worksite employees, master health plans as MEWAs, CPEO certification and bonds, state licensing, wage base restarts and exits.
- [Gross-to-Net, Step by Step](https://www.syntaqx.com/books/workforce/gross-to-net): Gross-to-net in order: earnings, pre-tax deductions, taxes, post-tax deductions, garnishments and net pay, the taxability matrix, rounding, gross-ups, arrears.
- [Federal Withholding & the W-4](https://www.syntaqx.com/books/workforce/federal-withholding): Federal income tax withholding: the 2020+ and legacy W-4, Pub 15-T 2026 percentage and wage bracket methods worked, exemptions, nonresidents and lock-ins.
- [Supplemental Wages & Imputed Income](https://www.syntaqx.com/books/workforce/supplemental-wages-and-imputed-income): Bonuses and commissions under the 22% flat and aggregate methods, the $1 million 37% rule, group-term life over $50,000, vehicles, other fringes and stock pay.
- [Pre-Tax & Post-Tax Deductions](https://www.syntaqx.com/books/workforce/deductions): Payroll deductions: Section 125, 401(k) and Roth with 2026 limits, HSA, FSA and commuter benefits, state quirks, after-tax items, ordering, arrears, memos.
- [Tips & the 2025 Tax Law](https://www.syntaqx.com/books/workforce/tips-and-the-2025-deductions): Tips in payroll: reporting, allocation and Form 8027, FICA on tips and the 45B credit, the P.L. 119-21 tips and overtime deductions, and the 2026 W-2 codes.
- [Retro Pay, Voids & Corrections](https://www.syntaqx.com/books/workforce/retro-pay-voids-and-corrections): Correcting payroll: off-cycle runs, retro raises and overtime, voids, reversals, manual checks, overpayment recovery, and fixes across quarters and years.
- [Payroll by Industry](https://www.syntaqx.com/books/workforce/payroll-by-industry): Industry payroll: restaurants, Davis-Bacon certified payroll, farms and H-2A, household employers, clergy, schools, 8 and 80, staffing and union shops.
- [FICA, FUTA & SUTA](https://www.syntaqx.com/books/workforce/fica-futa-and-suta): Social Security and Medicare with the 2026 wage base, Additional Medicare, FUTA and credit reduction states, SUTA wage bases, rates and successor rules.
- [Deposits, Returns & the Tax Calendar](https://www.syntaqx.com/books/workforce/deposits-and-returns): The lookback period, monthly and semiweekly deposits, the $100,000 next-day rule, EFTPS, Forms 941, 944, 943 and 940, penalties, and the tax calendar as data.
- [State & Local Payroll Taxes](https://www.syntaqx.com/books/workforce/state-and-local-tax): State withholding methods, flat and no-tax states, local income taxes from Pennsylvania to Oregon, registrations, and the jurisdiction lookup from an address.
- [Multi-State, Reciprocity & Remote Work](https://www.syntaqx.com/books/workforce/multi-state-and-remote-work): Resident and work states, reciprocity certificates, credits, New York's convenience rule, day thresholds, remote hires in new states and day-based allocation.
- [Tax Notices, Amendments & Agency Accounts](https://www.syntaqx.com/books/workforce/tax-notices-and-agency-accounts): Agency registration and account numbers, IRS and state notices, penalty relief and first-time abatement, Form 941-X, state amendments and the notice inbox.
- [Tax Engines & Filing Services](https://www.syntaqx.com/books/workforce/tax-engines-and-filing): The calculation layer and the file-and-remit layer, Symmetry, Vertex, ADP and MasterTax, location codes, rate updates, engine testing, 94x e-file and rejects.
- [Year-End, W-2s & Wage Reporting](https://www.syntaqx.com/books/workforce/year-end-and-w2s): The W-2 box by box with the 2026 changes, the W-3, EFW2 and BSO, reconciling to the 941s, state and local filings, W-2c, penalties and the January rush.
- [Funding a Payroll](https://www.syntaqx.com/books/workforce/funding-a-payroll): Collecting a payroll from the employer: debit timing from four-day to same-day, wire prefunding, credit limits, risk tiers, demotion and check date math.
- [When the Debit Fails](https://www.syntaqx.com/books/workforce/failed-debits-and-recovery): A payroll debit that comes back: the return codes that matter, retries, blocked payrolls, partial pay, recovery, who eats the loss, and the fraud patterns.
- [Client Funds & Impound Accounts](https://www.syntaqx.com/books/workforce/client-funds-and-impounds): Where a payroll provider holds clients' money: trust accounts, impounding, investment ladders, liquidity, client funds obligations and the daily reconciliation.
- [Direct Deposit, Pay Cards & Checks](https://www.syntaqx.com/books/workforce/paying-employees): How net pay reaches workers: direct deposit and splits, Reg E's compulsory use rule, payroll cards, paper checks, instant pay and unclaimed wages.
- [Child Support Withholding](https://www.syntaqx.com/books/workforce/child-support-withholding): Income withholding for child support: the IWO and e-IWO, timing, priority, the 50 to 65% limits, disbursement units, multiple orders, terminations and NMSNs.
- [Garnishments & Levies](https://www.syntaqx.com/books/workforce/garnishments-and-levies): Wage garnishment as payroll computes it: CCPA disposable earnings and limits, creditor orders, IRS levies and Pub 1494, student loans, bankruptcy and stacking.
- [When Payroll Providers Fail](https://www.syntaqx.com/books/workforce/when-providers-fail): When a payroll provider fails: MyPayrollHR and Cachet, diverted tax impounds, the liability that stays with the employer, and the controls that prevent it.
- [The Workweek & the Time Record](https://www.syntaqx.com/books/workforce/time-and-attendance): The FLSA workweek, what counts as hours worked, the 29 CFR 516 record, raw punches against rounding, edits, approvals and retention.
- [Clocks, Kiosks, Geofences & Biometrics](https://www.syntaqx.com/books/workforce/time-clocks-and-biometrics): Capturing punches: clocks, kiosks, mobile and geofenced punches, buddy punching, offline clocks, and biometric clocks under BIPA and other state laws.
- [Overtime & the Regular Rate](https://www.syntaqx.com/books/workforce/overtime-and-the-regular-rate): FLSA overtime and the regular rate: excludable pay, weighted averages, bonuses and retro overtime, state daily overtime, and the exempt salary level.
- [Minimum Wage as Data](https://www.syntaqx.com/books/workforce/minimum-wage-as-data): Minimum wage tables by federal, state and city level with effective dates, tipped and youth rates, indexing, which rate applies, and the table as a product.
- [Breaks, Premiums & Attestations](https://www.syntaqx.com/books/workforce/breaks-and-premiums): Meal and rest breaks as rules: California premiums as wages, attestations and waivers, other states, PUMP Act breaks, and how time systems enforce them.
- [Tipped Employees](https://www.syntaqx.com/books/workforce/tipped-employees): Tipped employees: the tip credit and state bans, tip pools and the manager rule, service charges, dual jobs, card fee deductions, payouts and records.
- [Fair Workweek & Scheduling Laws](https://www.syntaqx.com/books/workforce/scheduling-laws): Fair workweek laws as rules: advance notice, predictability pay, rest between shifts, on-call shifts, minors' hours, and premiums as earning codes.
- [Pay Frequency, Pay Statements & Final Pay](https://www.syntaqx.com/books/workforce/pay-frequency-statements-and-final-pay): State payday rules, required pay statement contents, final pay deadlines by state and separation type, waiting time penalties and PTO payout.
- [The HRIS as Record of Truth](https://www.syntaqx.com/books/workforce/hris-record-of-truth): The employee record and its history: effective dating, future-dated changes, corrections, positions, org units, and joiner, mover and leaver events to payroll.
- [Recruiting, ATS & AI in Hiring](https://www.syntaqx.com/books/workforce/recruiting-and-hiring): Requisitions, candidates, applications and offers, EEO self-identification after the 2026 rules, ATS APIs, AI hiring laws and candidate data retention.
- [Background Checks, Fair Chance & Drug Testing](https://www.syntaqx.com/books/workforce/background-checks-and-fair-chance): FCRA disclosure, authorization and adverse action, screening provider APIs, fair chance sequencing in California and NYC, cannabis testing laws and monitoring.
- [Onboarding: I-9, E-Verify & New Hire Reporting](https://www.syntaqx.com/books/workforce/onboarding-i9-and-new-hires): Form I-9 editions and timing, remote examination, reverification and retention, E-Verify cases and mismatches, state new hire reports and the W-4.
- [Pay Transparency, Pay Equity & EEO-1](https://www.syntaqx.com/books/workforce/pay-transparency-and-equity): Salary range posting laws as a rules table, salary history bans, state pay data reports, EEO-1's proposed rescission, the EU Directive and pay equity.
- [Terminations, Offboarding & WARN](https://www.syntaqx.com/books/workforce/terminations-and-warn): The separation fan-out, WARN counting over 30 and 90 days, state mini-WARN laws, severance and releases in payroll, unemployment claims and rehire.
- [Employee Records, Privacy & Retention](https://www.syntaqx.com/books/workforce/employee-records-and-privacy): Personnel file access laws, retention schedules by record, medical record separation, employee data under the CCPA, SSN truncation and legal holds.
- [FMLA Administration](https://www.syntaqx.com/books/workforce/fmla): FMLA eligibility from time records, the 12-week entitlement and leave year methods, notice and certification clocks, intermittent leave in hours, and records.
- [State Paid Family & Medical Leave](https://www.syntaqx.com/books/workforce/state-paid-leave): State disability and paid leave programs as payroll runs them: 2026 rates and wage bases, splits, small employer rules, private plans, wage reports and taxes.
- [Sick Leave & PTO Engines](https://www.syntaqx.com/books/workforce/sick-leave-and-pto): Paid sick leave laws as rules (accrual, caps, carryover, frontloading, waiting periods), PTO policies, California vacation as wages, payout and the ledger.
- [Enrollment & Life Events](https://www.syntaqx.com/books/workforce/enrollment-and-life-events): Open enrollment, new hire windows, Section 125 status changes, HIPAA special enrollment, EOI, dependent checks, tiers and rates, and deductions to payroll.
- [Carrier Connections & the 834](https://www.syntaqx.com/books/workforce/carrier-connections): The 834 from the employer side: change and full files, maintenance codes, TA1 and 999, connection setup and testing, API carriers, and invoice reconciliation.
- [The ACA Employer Mandate & 1095-C](https://www.syntaqx.com/books/workforce/aca-employer-mandate): ALE status, full-time measurement and look-back periods, 2026 affordability at 9.96%, 4980H penalties worked, Forms 1094-C and 1095-C codes, and Letter 226-J.
- [COBRA & State Continuation](https://www.syntaqx.com/books/workforce/cobra): COBRA's qualifying events, notice clocks, 60-day elections, 45-day first payments, 30-day grace, premiums up to 102%, administrators and state mini-COBRA laws.
- [401(k) Deferrals & Remittance](https://www.syntaqx.com/books/workforce/retirement-plan-deferrals): 2026 deferral limits, the Roth catch-up rule, auto-enrollment, matches and true-ups, plan compensation, deposit deadlines, VFCP and the recordkeeper file.
- [HSAs, FSAs & HRAs](https://www.syntaqx.com/books/workforce/hsa-fsa-and-hras): 2026 HSA, FSA and HRA limits, HDHP rules and the 2025 law, payroll contributions and seed money, carryover and grace, dependent care, QSEHRA and ICHRA.
- [Benefits Administration Platforms](https://www.syntaqx.com/books/workforce/benefits-platforms): Benefitfocus, Businessolver, Employee Navigator, Ease, Selerix and HCM suites, brokers, carrier APIs, plans, rates and eligibility as data, and payroll.
- [Contractors & 1099s](https://www.syntaqx.com/books/workforce/contractors-and-1099s): Contractor reporting: W-9s, TIN Matching, 24% backup withholding and B-notices, 1099-NEC and 1099-MISC at $2,000, IRIS after FIRE, and state filing.
- [Worker Classification](https://www.syntaqx.com/books/workforce/worker-classification): Employee or contractor under each test: the IRS common-law test and SS-8, Section 530, the DOL rule and its 2026 proposal, ABC tests, 3509 costs and VCSP.
- [Employer of Record & Global Employment](https://www.syntaqx.com/books/workforce/employer-of-record): EOR mechanics, owned entities and partners, contractor of record, permanent establishment risk, terminations abroad, pricing and when to open an entity.
- [International Payroll](https://www.syntaqx.com/books/workforce/global-payroll): Global payroll through aggregators and in-country partners, UK, Canada and Germany worked, EU rules that touch pay, currencies and rails, and data residency.
- [Embedded Payroll](https://www.syntaqx.com/books/workforce/embedded-payroll): Payroll sold as an API to vertical software: Check, Gusto Embedded, Zeal and others, object models, onboarding, run states, webhooks and who carries the risk.
- [Unified HR & Payroll APIs](https://www.syntaqx.com/books/workforce/unified-hr-apis): Finch, Merge and others: one API over hundreds of payroll and HR systems, read and write scopes, assisted connections, sync cadence and deduction write-back.
- [Payroll Platform Architecture](https://www.syntaqx.com/books/workforce/payroll-architecture): The pay run engine as a replayable function, versioned rules, as-of reads, idempotent money, schedulers, tenancy, peak loads, GL exports and testing.
- [Changing Providers Mid-Year](https://www.syntaqx.com/books/workforce/changing-providers): Switching payroll mid-year: Rev. Proc. 2004-53 standard vs alternate, successor wage bases, YTD loading at quarter boundaries, parallel runs, PEOs and go-live.
- [Controls, Audits & SOC 1](https://www.syntaqx.com/books/workforce/controls-audits-and-soc1): What a payroll SOC 1 covers, user entity controls, internal controls over payroll, and what DOL, IRS and state UI auditors ask for, with the records each needs.
- [Payroll Fraud & Security](https://www.syntaqx.com/books/workforce/payroll-fraud-and-security): Direct deposit diversion and email compromise, W-2 phishing, ghost employees, time theft, portal takeover, insider risk, SSN and bank data, and what works.
- [Payroll & HR Metrics](https://www.syntaqx.com/books/workforce/workforce-metrics): Clients, worksite employees, retention, PEPM, float and yield as filings define them; on-time pay, notice and correction rates; turnover and time to hire.
- [Workforce Glossary](https://www.syntaqx.com/books/workforce/glossary): Payroll and HR terms by part: the business, gross to net, payroll tax, money movement, wage-hour, HR records, leave, benefits, contractors and global payroll.