Federal Insurance Contributions Act

Editorial approval scope: The team checked current source fidelity, scope boundaries, dates, arithmetic, reader usefulness, practical workflow, and general-information limitations.

FICA contains two tax components

The IRS 2026 Publication 15 explains that FICA provides old-age, survivors, disability, and hospital insurance. Social Security tax finances the first component; Medicare tax finances hospital insurance. Each tax is calculated and reported separately.

Employers generally withhold the employee share from covered wages and pay a matching employer share. Exceptions apply to specified workers, services, and payments, so the payroll system needs a documented taxability decision rather than a universal “employee equals FICA” switch.

The 2026 rates use different wage bases

For 2026, Publication 15 states:

• Social Security tax is 6.2% for the employee and 6.2% for the employer on covered wages up to the $184,500 annual wage base.
• Medicare tax is 1.45% for the employee and 1.45% for the employer, with no wage-base ceiling.

These amounts change by law or annual adjustment. Store the tax year with every rate table and prevent a prior-year configuration from carrying into January unnoticed.

Additional Medicare Tax has a separate employee-withholding rule when wages paid by an employer exceed the statutory threshold. The employer begins withholding under the IRS rule regardless of the employee's filing status. There is no matching employer Additional Medicare Tax.

Taxable wages differ from gross cash paid

FICA wages can include regular pay, overtime, bonuses, certain fringe benefits, and other compensation. Specific exclusions can apply to qualified health-plan contributions, retirement contributions, dependent care, and other benefits depending on their structure.

Map each earning and deduction code to federal income-tax, Social Security, Medicare, FUTA, and state treatment separately. One pretax label cannot answer every tax. Publication 15-B, plan documents, and current specialist advice may be needed for benefits.

Classification comes before calculation

Employee versus independent-contractor status affects employment taxes. A contract label does not decide classification. Review the actual relationship under applicable federal and state tests.

When a worker is an employee, collect and validate required payroll records, apply the correct employer EIN, and preserve work-state and resident-state facts. Moving between related entities can affect wage-base administration under specialized rules; do not restart Social Security withholding merely because a local payroll profile changed.

Withholding, deposit, and reporting are separate controls

Payroll calculates withholding and the employer share. The employer then deposits federal taxes on its assigned schedule and reports them on the applicable employment-tax return, often Form 941. A correct paycheck does not prove a timely deposit or accurate return.

Track payroll date, liability date, deposit due date, amount, confirmation, return period, filing acceptance, and general-ledger entry. Deposit frequency depends on IRS lookback and special rules rather than a practice's pay frequency.

The current Form 941 instructions should control quarterly reporting. Schedule B and other attachments depend on depositor status and facts.

A fictional payroll reconciliation

Shorebird ABA processes a biweekly payroll for 40 employees. Thirty-nine employee rows reconcile from taxable Social Security and Medicare wages through employee withholding, employer share, deposit file, quarter-to-date ledger, and W-2 accumulator. One row remains held because a fringe-benefit tax code changed midperiod.

Reconciliation completeness is 39 of 40 employees, or 97.5%. The held employee stays in the denominator and the filing worklist. Payroll corrects the taxability decision before releasing the deposit and preserves the original calculation and approved change.

This ratio measures source agreement. It does not prove the worker classification, tax treatment, deposit timing, or return is legally correct.

Reconcile quarterly returns to Forms W-2

Quarterly Social Security and Medicare wages and taxes should reconcile to payroll registers, deposits, the general ledger, and year-end Forms W-2 and W-3. Investigate differences from rounding, third-party sick pay, timing, corrections, voided checks, or entity mapping.

The IRS Topic 751 summarizes current Social Security and Medicare rates. Use detailed instructions for calculations and corrections. An amended payroll register alone does not correct an already filed return or employee statement.

Corrections need coordinated records

Errors may require payroll adjustment, Form 941-X, W-2c and W-3c, employee repayment or reimbursement, deposit work, and state corrections. The proper route depends on error type, timing, and whether tax was withheld.

Use a qualified reviewer, preserve affected periods, communicate clearly with employees, and close every artifact. Avoid netting an old error into a later paycheck without confirming that method is allowed.

Test backup filing access before each quarter closes and document who can release a deposit during an absence.

At the start of each calendar year, lock the approved Social Security wage base and rates, Medicare rates, Additional Medicare threshold handling, deposit schedule, and form versions. Test employees below, at, and above each threshold. Preserve the approved configuration and rerun tests after payroll updates or entity migrations.