Glossary of factor symbols

Who this is for: Developers reading API breakdown fields or CONFORMANCE vectors who need plain English for each symbol.

When you finish: You can map any factor symbol in a response to its T4127 (Payroll Deductions Formulas) step and open the CRA payroll formulas hub.

Amounts in API responses are decimal strings in cents; this page defines names only.

A

Annual taxable income.

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

R

Federal tax rate that applies to the annual taxable income A.

Source: T4127 Chapter 8, Table 8.1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K

Federal constant; the tax overcharged when applying the higher federal rates to A.

Source: T4127 Chapter 8, Table 8.1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K1

Federal non-refundable personal tax credit (lowest federal tax rate × TC).

Source: T4127 Chapter 4, Step 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K2

Federal tax credit for base CPP contributions and EI premiums for the year.

Source: T4127 Chapter 4, Step 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K4

Federal non-refundable tax credit calculated using the Canada employment amount.

Source: T4127 Chapter 4, Step 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

T3

Annual basic federal tax.

Source: T4127 Chapter 4, Step 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

T1

Annual federal tax deduction.

Source: T4127 Chapter 4, Step 3

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

V

Provincial or territorial tax rate for the year.

Source: T4127 Chapter 8, Table 8.1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

KP

Provincial or territorial constant.

Source: T4127 Chapter 8, Table 8.1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K1P

Provincial or territorial non-refundable personal tax credit (lowest provincial rate × TCP).

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K2P

Provincial or territorial tax credit for base CPP contributions and EI premiums for the year.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

T4

Annual basic provincial or territorial tax.

Source: T4127 Chapter 4, Step 4

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

V1

Provincial surtax calculated on the basic provincial tax (Ontario only).

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

V2

Ontario Health Premium calculated on taxable income.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

S

Provincial tax reduction (Ontario and British Columbia).

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

T2

Annual provincial or territorial tax deduction (except Quebec).

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

T

Estimated federal and provincial or territorial tax deductions for the pay period: round((T1+T2)/P)+L. This is the combined Step 6 quotient. It may differ by one cent from employee.total_tax, which is the sum of the separately rounded federal and provincial lines PDOC displays (round(T1/P)+L and round(T2/P)). Compare screen totals to employee.total_tax; keep breakdown.T as the T4127 figure.

Source: T4127 Chapter 4, Step 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

TB

Tax on the current bonus or retroactive pay: the difference between annual tax (T1+T2) with the non-periodic payment and without it, floored at zero. If A with the bonus is at or below $5,000, a flat 15% (10% Quebec) of the bonus is used instead.

Source: T4127 Chapter 4, bonuses and retroactive pay

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

M

Year-to-date federal and provincial tax already deducted on periodic pay (Option 2). Does not include extra tax requested (L) or tax on bonuses (M1).

Source: T4127 Chapter 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

M1

Accumulated federal and provincial tax deductions on non-periodic payments such as bonuses, to the last pay period (Option 2).

Source: T4127 Chapter 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

C

Canada (or Quebec) Pension Plan contributions for the pay period.

Source: T4127 Chapter 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

C2

Second additional Canada (or Quebec) Pension Plan contributions for the pay period.

Source: T4127 Chapter 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

EI

Employment insurance premiums for the pay period.

Source: T4127 Chapter 7

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

F5

Deductions for Canada Pension Plan additional contributions for the pay period.

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

BPAF

Federal Basic Personal Amount.

Source: T4127 Chapter 2; Table 8.2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K3

Other federal non-refundable tax credits authorized by a tax services office or tax centre.

Source: T4127 Chapter 4, Step 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K3P

Other provincial or territorial non-refundable tax credits authorized by a tax services office or tax centre.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K4P

Territorial non-refundable tax credit calculated using the provincial or territorial Canada employment amount.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

K5P

Provincial supplemental non-refundable tax credit (lowest provincial tax rate).

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

LCF

Federal labour-sponsored funds tax credit.

Source: T4127 Chapter 4, Step 3

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

LCP

Provincial or territorial labour-sponsored funds tax credit.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

Y

Additional Ontario tax-reduction amount based on the number of eligible dependants, used in Factor S.

Source: T4127 Chapter 4, Step 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

F5A

CPP additional-contribution deduction for the pay period taken from periodic income.

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

F5B

CPP additional-contribution deduction for the pay period taken from the non-periodic payment.

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

D

Employee’s year-to-date (before the pay period) Canada Pension Plan contribution with the employer.

Source: T4127 Chapter 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

D1

Employee’s year-to-date (before the pay period) employment insurance premium with the employer.

Source: T4127 Chapter 7

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

D2

Employee’s year-to-date (before the pay period) second additional CPP contribution with the employer.

Source: T4127 Chapter 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

P

The number of pay periods in the year.

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

PR

The number of pay periods left in the year (including the current pay period).

Source: T4127 Chapter 4, Step 1

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

PM

Total months during which CPP and/or QPP contributions are required (used to prorate the maximum contribution).

Source: T4127 Chapter 6

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

S1

Option 2 cumulative-averaging pair: total pay periods / current pay-period number (for example 52/1, 52/2). Never a binary float. Option 1 serializes as P/1.

Source: T4127 Chapter 5

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

CEA

Canada Employment Amount, a non-refundable tax credit used in the calculation for K4 and K4P.

Source: T4127 Chapter 8, Table 8.2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

TC

Total claim amount reported on federal Form TD1.

Source: T4127 Chapter 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

TCP

Total claim amount reported on the provincial or territorial Form TD1.

Source: T4127 Chapter 2

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

IE

Insurable earnings for the pay period, including insurable taxable benefits, bonuses, and retroactive pay increases.

Source: T4127 Chapter 7

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

QPIP

Quebec Parental Insurance Plan premium for the pay period.

Source: T4127 Chapter 8, Table 8.29

CRA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll/payroll-deductions-formulas.html

Last reviewed: 2026-09-20

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