Parameter Taxonomy

Parameter names have two fixed components; the first component is the tax category abbreviation and the second is the abbreviation for the function of the parameter’s value. In some cases, parameter names have a subcategory that conveys additional information about the parameter (see examples).

Tax categories

Tax categories are uppercase:

ACTC: Additional Child Tax Credit

ALD: Above-the-line Deduction

AMED: Additional Medicare

AMT: Alternative Minimum Tax

CDCC: Child and Dependent Care Credit

CG: Capital Gain

CTC: Child Tax Credit

DCC: Dependent Care Credit

EITC: Earned Income Tax Credit

ETC: Education Tax Credit

FEI: Foreign Earned Income

FICA: Federal Income Contributions Act

ID: Itemized Deduction

II: Individual Income (including personal exemptions and tax brackets)

KT: Kiddie Tax

LLC: Lifetime Learning Credit

MED: Medicare

NIIT: Net Investment Income Tax

SS: Social Security

STD: Standard Deduction

Functions of the parameter’s value

Functions of the parameter’s value are lowercase:

c: ceiling

e: end

ec: exclusion

em: exemption

f: floor

HC: haircut [1]

p: phaseout

rt: rate

s: start

t: tax

thd: threshold

Combine functions to create additional functions: frt = floor rate.

Examples

_AMT_em: Alternative Minimum Tax exemption amount

_ID_ps: Itemized Deduction phaseout Adjusted Gross Income start (Pease)

_AMT_tthd: Alternative Minimum Tax surtax threshold

_SS_Earnings_c: Maximum taxable earnings for Social Security

_AMT_Child_em: Child Alternative Minimum Tax exemption additional income base

_ETC_pe_Married: Education Tax Credit phaseout ends (Married)

[1]	Currently, the abbreviation for haircuts is uppercase in the Tax Calculator; we will be changing it to lowercase in the future and will update this page accordingly.