Method Deck / tax

FICA payroll tax, by stated table

Computes employee-side FICA tax (Social Security, Medicare, and Additional Medicare Tax) on a given amount of annual wages, using a stated, cited FICA table.

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Inputs

• annual_wages (number, currency units, required) min 0 : Total annual wages subject to FICA
• filing_status (string, required) one of: single, married_filing_jointly, head_of_household : Filing status, used only for the Additional Medicare Tax threshold
• social_security_wage_base (number, currency units, required) min 0 : The Social Security (OASDI) taxable wage base for the year being computed; indexed annually by the SSA.
• social_security_rate_percent (number, %, required) min 0 : Employee-side Social Security tax rate.
• medicare_rate_percent (number, %, required) min 0 : Employee-side Medicare tax rate, applied to all wages with no cap.
• additional_medicare_rate_percent (number, %, required) min 0 : Additional Medicare Tax rate on wages above the filing-status threshold.
• additional_medicare_threshold_mfj (number, currency units, required) min 0 : Additional Medicare Tax threshold for married filing jointly.
• additional_medicare_threshold_other (number, currency units, required) min 0 : Additional Medicare Tax threshold for single or head of household.
• fica_table_source (string, required) : Citation for the wage base, rates, and thresholds above; change it together with all six values when using a newer year's table.
• fica_table_date (string, ISO date, required) : The date the cited FICA table was retrieved or published.

Outputs

• social_security_tax (currency units): social_security_rate_percent of wages up to social_security_wage_base
• medicare_tax (currency units): medicare_rate_percent of all wages
• additional_medicare_tax (currency units): additional_medicare_rate_percent of wages above the filing-status threshold
• total_fica_tax (currency units): Sum of the three components

Steps

1. The visitor supplies social_security_wage_base, social_security_rate_percent, medicare_rate_percent, additional_medicare_rate_percent, both Additional Medicare Tax thresholds, plus fica_table_source and fica_table_date; this method never looks up a table itself. Replace all eight together to use a newer official table.
2. social_security_tax = social_security_rate_percent / 100 * min(annual_wages, social_security_wage_base).
3. medicare_tax = medicare_rate_percent / 100 * annual_wages (no wage base cap).
4. additional_medicare_tax = additional_medicare_rate_percent / 100 * max(0, annual_wages - threshold), where threshold is additional_medicare_threshold_mfj for married filing jointly, otherwise additional_medicare_threshold_other.
5. total_fica_tax = social_security_tax + medicare_tax + additional_medicare_tax.
6. Round every component to 2 decimals (money to cents).

Constants

• social_security_wage_base_2026 = 184500 currency units (source)
• social_security_rate = 0.062 rate (source)
• medicare_rate = 0.0145 rate (source)
• additional_medicare_rate = 0.009 rate (source)
• additional_medicare_threshold_mfj = 250000 currency units (source)
• additional_medicare_threshold_other = 200000 currency units (source)

Sources

• Contribution and Benefit Base (2026 Social Security taxable maximum: $184,500) (Social Security Administration, 2026-09-30T19:31:29Z) - SSA's official 2026 OASDI wage base, announced with the October 2025 COLA determination; documented source of the social_security_wage_base default value.
• Topic no. 560, Additional Medicare Tax (Internal Revenue Service, 2026-09-30T19:31:29Z) - Medicare tax rate 1.45% with no wage cap; Additional Medicare Tax of 0.9% above statutory (not inflation-adjusted) thresholds of $250,000 MFJ / $200,000 single or head of household; documented source of the rate and threshold default values.

Worked example and test vectors

Published card

• Address: 6d1b328080222c194cbcfaac71f3878b
• Made at: 2026-09-30T22:39:30.722Z
• Method sha256: f1319e9325f89c7a5aa44535780989d68fad1d4ebbda724b9faf6d1595701ccd