Australia (2019-2020 Income tax year)
This chapter includes data on the income taxes paid by workers, their social security contributions, the family benefits they receive in the form of cash transfers as well as the social security contributions and payroll taxes paid by their employers. Results reported include the marginal and average tax burden for eight different family types.
Methodological information is available for personal income tax systems, compulsory social security contributions to schemes operated within the public sector, universal cash transfers as well as recent changes in the tax/benefit system. The methodology also includes the parameter values and tax equations underlying the data.
The national currency is the Australian dollar (AUD). For the 2019-2020 income tax year AUD 1.47 was equal to USD 1. The average full time worker earned AUD 90 861 in 2019-2020.
1.1. Federal income tax
1.1.2. Tax allowances and credits
1.1.2.1. Standard tax reliefs
Basic reliefs: Income earned up to AUD 18 200 by resident taxpayers is subject to tax at a zero rate.
Relief(s) for children: See Section 4.2 for more detail on transfers related to dependent children.
Relief for social security contributions and other taxes: No such contributions are levied.
Reliefs for low income earners: A tax offset worth a maximum of AUD 445 is available for low income earners called the Low Income Tax Offset. Taxpayers whose taxable income was less than AUD 37 000 in 2019-2020 are eligible to receive the full amount of the offset. The offset is reduced by AUD 0.015 for every AUD 1 by which a taxpayer’s taxable income exceeds AUD 37 000 and is no longer available once a taxpayer’s taxable income exceeds AUD 66 667.
Reliefs for Low and Middle Income Earners: A tax offset worth a maximum of AUD 1080 is available for taxpayers with earnings up to AUD 126 000 called the Low and Middle Income Tax Offset. Taxpayers whose taxable income was less than AUD 37 000 in 2019-2020 are eligible to receive AUD 255. The offset is increased by AUD 0.075 for every AUD 1 by which a taxpayer’s taxable income exceeds AUD 37 000 up to a maximum of AUD 1 080 when the taxpayer’s earnings are between AUD 48 000 and AUD 90 000. The offset is then reduced by AUD 0.03 for every AUD 1 by which a taxpayers earnings exceed AUD 90 000 and is no longer available once a taxpayer’s taxable income exceeds AUD 126 000.
Relief for recipients of certain social security benefits: The Beneficiary Tax Offset is available for those who receive certain taxable social security benefits called ‘rebatable benefits’. It ensures that a person who is wholly or mainly dependent on rebatable benefits, and does not have any other taxable income, is not liable for income tax. The amount of the Beneficiary Tax Offset available to an individual is determined by the total amount of the rebatable benefit(s) they receive in an income year.
Relief for taxpayers who maintain a dependant who is genuinely unable to work: A taxpayer who maintains a dependant who is genuinely unable to work due to invalidity or carer obligations may be eligible for the Dependent (Invalid and Carer) Tax Offset. This tax offset is worth a maximum of AUD 2 766 in 2019-2020. To qualify for the offset in 2019-2020, the combined adjusted taxable income of the taxpayer and their spouse (where one exists) should not exceed AUD 100 000. The amount of offset that may be received is reduced by AUD 1 for every AUD 4 by which the dependant's adjusted taxable income exceeds AUD 282 and is no longer available once the dependant’s adjusted taxable income exceeds AUD 11 346. This offset is not included in the Taxing Wages model.
Relief for pensioners and seniors. The Seniors and Pensioners Tax Offset (SAPTO) is available to recipients of taxable Government Pensions, including Parenting Payment Single. SAPTO is also available to Australians who meet all of the Age Pension eligibility criteria except the income and/or asset tests. SAPTO is worth up to AUD 2 230 for a single taxpayer, up to AUD 1 602 for each member of a senior couple not separated by illness and AUD 2 040 for each member of a senior couple separated by illness. The offset is withdrawn at the rate of AUD 0.125 for every AUD 1 that a recipient’s income exceeds their relevant shade out threshold dependent on their circumstances. For a single taxpayer, this means that the offset is withdrawn from AUD 32 279 and is no longer available once income reaches AUD 50 119. For members of a couple not separated by illness, the offset is withdrawn from a combined income of AUD 57 948 and is no longer available once combined income reaches AUD 83 580.
1.1.2.2. Main non-standard tax reliefs applicable to an average worker include:
Relief for superannuation: Contributions to a low income spouse’s superannuation attract an 18% rebate up to a maximum rebate of AUD 540. In 2019-2020, the Low Income Superannuation Tax Offset matches AUD 0.15 for each AUD 1 of concessional contributions from at least AUD 10 up to AUD 500 a year for eligible individuals with annual incomes up to AUD 37 000. In addition in 2019-2020, eligible individuals with incomes not exceeding AUD 53 564 can make non-concessional contributions and receive a co-contribution of 50%, up to a maximum of AUD 500.
Relief for private health insurance: For the 2019-2020 income year, there are different rebate amounts depending on age and income. For individuals below 65 years without dependants and with annual income for surcharge purposes below AUD 90 000 the rebate is 25.059% of the cost of cover for eligible private health care. For families (couples and individuals with at least one dependent child) below 65 years with annual income for surcharge purposes below AUD 180 000, the rebate is 25.059% of the cost of cover for eligible private health care. The threshold is increased by AUD 1 500 for each dependent child after the first.
The rebate percentages are reduced for individuals and families with annual incomes above these amounts. The rebate percentages are also higher for individuals and families aged 65 years or more.
Other non-standard reliefs provided as deductions are:
subscriptions paid in respect of membership of a trade, business or professional association or union;
charitable contributions of AUD 2 or more to specified funds, authorities and institutions, including public benevolent institutions, approved research institutes for scientific research, building funds for schools conducted by non-profit organisations etc.; and
work-related expenses including cost of replacement of tools of trade, cost of provision and of cleaning protective clothing and footwear, travelling between jobs or travelling in the course of employment.
1.1.3. Tax schedule
General rates of tax - resident individuals
To nominally contribute towards the cost of basic medical and hospital care a Medicare Levy is imposed on the taxable incomes of resident taxpayers. In 2019-2020 the levy applied at the rate of 2.0% of the taxable income of an individual.
Certain thresholds are applied before the levy is imposed. For taxpayers aged under Age Pension age in 2019-2020, an individual was not liable for the levy where their taxable income did not exceed AUD 22 801. A taxpayer in a couple or sole parent family who is not receiving Parenting Payment, (see section 4.2), does not pay the levy if the taxable family income does not exceed AUD 38 474. The threshold is increased by AUD 3 533 for each dependent child. Where an individual’s taxable income exceeds AUD 22 801, or a family’s income exceeds AUD 38 474 (plus AUD 3 533 for each dependent child), the levy shades in at a rate of 10% of the excess of taxable income over the threshold, until the levy is equal to 2.0% of the individual’s or family’s taxable income.
For 2019-2020, individual senior Australians of Age Pension age were not liable to pay the levy where their taxable income did not exceed AUD 36 056. Where taxable income exceeded AUD 36 056 but did not exceed AUD 45 070, the levy liability was equal to 10% of the excess of taxable income over AUD 36 056. Pensioner families (including couples and sole parents on Parenting Payment) and senior Australian families of Age Pension age, did not become liable to pay any Medicare levy until their combined income in 2019-2020 exceeded AUD 50 191 (plus AUD 3 533 for each dependent child).
Individual taxpayers who had income for surcharge purposes greater than AUD 90 000 in 2019-2020 (or if a couple had a combined income greater than AUD 180 000) but who did not have a complying private health insurance policy, were liable for the Medicare levy surcharge, which is applied as a flat rate on their taxable income and reportable fringe benefits. The surcharge rates are 1%, 1.25% and 1.5% depending on the taxpayer’s income for surcharge purposes above these thresholds. However, affected taxpayers typically purchase a complying policy as the cost of such a policy is generally less than the surcharge. The surcharge is therefore not included in this publication.
2.1. Employees’ contributions
None. There is, however, a Medicare Levy which is based upon taxable income. See Section 1.1.3.
2.2. Employers’ contributions
No contributions are collected from employers or employees specifically for pensions, sickness, unemployment or work injury benefits, family allowances or other benefits.
Part of Australia’s retirement income system is the provision of compulsory employer contributions (the Superannuation Guarantee system). In 2019-2020 the Superannuation Guarantee required employers to pay 9.5% on top of employees’ gross ordinary time earnings to an approved superannuation fund, provided they earn more than AUD 450 per month (they may also choose to make contributions for workers earning less than this threshold). This threshold is not indexed. There is also a limit to the Superannuation Guarantee. In each quarter any earnings beyond a threshold are not covered by the Superannuation Guarantee. This threshold is indexed to a measure of average earnings. In the 2019-2020 tax year this threshold was AUD 55 270 per quarter. The Superannuation Guarantee rate will remain at 9.5% until 2020-2021, then increase by 0.5 percentage points each year until it reaches 12% in 2025-26.
These contributions are not reflected in the ‘Taxing Wages’ calculations because they are not a form of taxation (they are not an unrequited transfer to general government). While employers are legislatively required to make contributions to approved superannuation funds, superannuation funds are private, although subject to regulation. Employers’ contributions are generally made to individual accounts and form part of employees’ personal superannuation assets. Some defined benefit schemes for public sector employees and private defined benefit schemes also exist. The employee may take superannuation benefits as either a lump sum payment or pension on retirement. Accordingly, superannuation contributions are reflected in the Non-Tax Compulsory Payment calculations.
3.1. Pay-roll tax
Australian State Governments levy pay-roll taxes on wages, cash or in kind, provided by larger employers to their employees. The rates of pay-roll tax, thresholds and deductions differ between States. In New South Wales, the State with the largest population, the pay-roll tax rate in 2019-2020 was 5.45% for employers with total Australian wages in excess of AUD 900 000. Employers are entitled to an exemption from tax, or a pro-rated pay-roll tax threshold, on wages paid in New South Wales up to a maximum of AUD 900 000. The exempt amount is reduced based on the proportion of the employer’s New South Wales pay-roll to its total Australian pay-roll.
4.1. Transfers related to marital status
There are no cash transfers made on a universal basis to married couples.
4.2. Transfers related to dependent children
Family Tax Benefit (FTB) Part A is paid to a parent, guardian or an approved care organisation to help families meet the costs of raising children. For 2019-2020, the base rate of FTB(A) is payable where the combined adjusted taxable income of the family does not exceed AUD 98 988. The payment shades out at the rate of AUD 0.30 per AUD 1 of income over the ceiling until the payment is nil. The base rate of payment is AUD 1 558.55 per annum for dependent children aged under 18 and for dependent full time students aged 16 to 19. A higher FTB(A) benefit is available for lower income earners, and the value of this benefit is dependent on the age and number of children. For 2019-2020 families may receive a maximum payment of AUD 4 854.50 for each child aged under 13 years and AUD 6 314.50 for each child aged 13 to 15 years and for each child aged 16 to 19 in full time secondary school. For 2019-2020 an end of year supplement of AUD 766.50 per child is also available for families with a combined adjusted taxable income of less than AUD 80 000. For 2019-2020, the higher benefit tapers out at the rate of AUD 0.20 for each dollar of income over AUD 54 677 until the base payment is reached. However, people receiving any social security allowances or pensions automatically qualify for the maximum higher benefit. The attached calculations assume each dependant is between 5 and 12 years of age.
Family Tax Benefit Part B (FTB(B)) is targeted at single income couple and sole parent families. Eligibility for FTB(B) is contingent upon having a child under the age of 16 or a qualifying dependent full-time student up to of the end of the calendar year they turn 18. There are two separate income tests applied to the parent(s). The parent earning the higher amount (or the sole parent, in the case of single parent families) must have an adjusted taxable income less than AUD 100 000 for the financial year for the family to be eligible. A secondary earner income threshold is also applied to the parent earning the lower amount. For 2019-2020, this threshold is AUD 5 694, above which the entitlement is reduced by AUD 0.20 for each dollar of income. There is no secondary earner income test applied to sole parents. For 2019-2020, the maximum payment is AUD 3 255.80 if the youngest dependent child is aged between 5 and 15 (or up to the end of the calendar year they turn 18 years if the dependent child is a full-time student), and AUD 4 500.45 if there is at least one child under 5 years. The attached calculations assume each dependant is between 5 and 12 years of age
Recipients of the Family Tax Benefit may elect to receive the benefit in fortnightly instalments or as an end of year lump sum payment.
A Newborn Supplement and Newborn Upfront Payment may be paid to families for each baby born from 1 March 2014. To be eligible families will need to be eligible for FTB(A) and not be accessing Parental Leave Pay for that child. For multiple births, Parental Leave Pay may be payable for one child and Newborn Supplement for the other child or children. The total value of the Newborn Supplement and Newborn Upfront Payment in 2019-2020 is up to AUD 2 239.86 for the first child (and all multiple births) and up to AUD 1 120.56 for subsequent children. This supplement and upfront payment replace the previous Baby Bonus.
On 1 January 2011 Australia’s first Paid Parental Leave scheme commenced. The scheme provides two government-funded payments: Parental Leave Pay and Dad and Partner Pay. Parental Leave Pay (PLP) provides the primary carer of a child with 18 weeks’ pay at the national minimum wage (AUD 740.80 per week before tax in 2019-2020), in the year following the child’s birth or adoption. The primary carer must have worked for at least 10 of the 13 months prior to the birth or adoption, and for at least 330 hours in that 10 month period with no more than an eight week gap between two working days. The primary carer’s adjusted taxable income must be AUD 150,000 or less in the financial year prior to the date of claim or date of birth or adoption, whichever is earlier. PLP and Newborn Supplement cannot be paid for the same child. A person cannot claim FTB(B) or the dependent spouse, child housekeeper and housekeeper tax offsets while they are receiving PLP.
Dad and Partner Pay (DAPP) provides the father or partner of the primary carer of a child with two weeks’ pay at the national minimum wage (AUD 740.80 per week before tax in 2019-20), in the year following the child’s birth or adoption. The father or partner must have worked for at least 10 of the 13 months prior to the birth or adoption and for at least 330 hours in that 10 month period with no more than an eight week gap between two working days. The father or partner’s adjusted taxable income must be AUD 150,000 or less in the financial year prior to the date of claim or date of birth or adoption, whichever is earlier. DAPP and PLP may be paid for the same child.
Child Care Subsidy (CCS) replaced the previous Child Care Benefit (CCB) and Child Care Rebate (CCR) from 2 July 2018. CCS is a means-tested payment which assists families with the cost of approved child care. CCS is payable to eligible families with incomes up to AUD 352 453. A percentage of the cost of childcare is subsidised, with the applicable percentage varying from 85 per cent for families with income less than AUD 68 163 to 20 per cent for families with income between AUD 342 453 and AUD 352 453. CCS to families with income above AUD 188 163 are capped at AUD 10 373 per child. The attached calculations assume no child care usage.
Parenting Payment is a taxable payment payable to low income families with responsibility for the care of a young child. Partnered persons are eligible if they have a qualifying child under six years of age, and sole parents are eligible if they have a qualifying child under eight years of age. In 2019-2020 the maximum annual amount of Parenting Payment (Partnered) (PP(P)) was AUD 13 146.90. Only one parent in a couple can be entitled to PP(P). The maximum annual amount of Parenting Payment (Single) (PP(S)) was AUD 20 336.40. These payments are subject to income and assets tests. The PP(P) tapers out at a rate of AUD 0.50 per AUD 1 of income over AUD 2,704 up to AUD 6,604 and reduces at a rate of AUD 0.60 per AUD 1 for income over AUD 6,604. Under the PP(P) income test, a spouse receives a reduced Parenting Payment, tapering at a rate of AUD 0.60, when the higher earning partner’s income exceeds AUD 25 674. If the spouse has little or no income (less than AUD 2,704 per annum), he or she would not receive any Parenting Payment when the higher earning partner’s income exceeds AUD 45 296. PP(S) reduces by AUD 0.40 for each AUD 1 of income above AUD 4 903.60 plus AUD 639.60 for each child other than the first. The attached calculations assume dependants are aged six and seven.
JobSeeker Payment replaced the Newstart Allowance on 20 March 2020 as the primary taxable payment payable to people aged from 22 years to Age Pension age (currently 66 years) who are unemployed or are regarded as unemployed, combining seven other payments. JobSeeker Payment is also payable to a member of a couple if their youngest child is aged 6 years or more and to single parents if their youngest child is aged 8 years or more. It is conditional on recipients fulfilling a personal Job Plan, which typically involves taking part in activities such as job seeking and training. In 2019-2020 the annual JobSeeker (or Newstart prior to 20 March 2020) amount for singles without dependants was AUD 14 561.10 and for partnered individuals was AUD 13 146.90. These payments taper out at a rate of AUD 0.50 per AUD 1 for incomes between AUD 2,704 and AUD 6,604, and reduce at a rate of AUD 0.60 per AUD for incomes over AUD 6,604. Under the thresholds and taper rates that applied in 2019-2020, the JobSeeker payment may be available to some full time workers under the OECD definition of 30 or more hours per week. The JobSeeker Payment for partnered individuals reduced by AUD 0.60 for each AUD 1 of their partner’s income above AUD 25 674. For single principal carers with dependent child or children, it reduced at a rate of AUD 0.40 per AUD 1 for incomes over AUD 2,704.
A non-taxable supplementary payment called Pharmaceutical Allowance (PA) is payable to eligible persons to help with medicine costs; for example, persons who receive the PP(S). PA is added to the maximum basic rate of PP(S) before a person’s PP(S) entitlement is calculated. Anyone with a PP(S) entitlement, after PA has been added, receives the full amount of PA. For 2019-2020, the payment is AUD 161.20.
A non-taxable Telephone Allowance is available on a quarterly basis to eligible individuals, including individuals who receive PP(S). The basic rate of the Telephone Allowance is AUD 120.20 for 2019-2020.
4.3. Other transfers
The Energy Supplement (ES) is an extra payment to help with energy costs, paid alongside certain income support payments. The ES is not indexed. The amount of the supplement varies depending on the main income support payment. FTB(A) and FTB(B) recipients are only eligible for the ES if they have been continuously eligible for their payment since 19 September 2016.
For eligible FTB(A) recipients, the maximum amount of ES is AUD 91.25 per year for each child under 13 years and AUD 116.80 for each child aged 13 to 19 years.
For eligible FTB(B) recipients, the amount of ES is AUD 73.00 per year for each child under 5 years, and AUD 51.10 per year for each child aged 5 to 18 years.
Recipients of PP(P) receive AUD 205.40 annually, and recipients of PP(S) receive AUD 312.
For JobSeeker Payment/Newstart Allowance recipients, the ES is AUD 228.80 annually for singles without dependents, and AUD 205.40 for partnered individuals.
The calculations assume families and individuals are eligible for the energy supplement as a significant proportion of FTB(A) and FTB(B) recipients were eligible for the supplement in 2019-2020.
Single Income Family Supplement
The Single Income Family Supplement (SIFS) is a non-taxable annual payment of up to AUD 300 for households with one main income earner with taxable income between AUD 68 000 and AUD 150 000 and who receive FTB for at least one child. This payment is being phased out from 1 July 2017.
The SIFS phases in at a rate of AUD 0.025 for every AUD 1 above AUD 68,000 until it reaches AUD 300 at AUD 80,000 where it remains constant at AUD 300. Once the main earner’s income exceeds AUD 120,000 the SIFS reduces by AUD 0.01 for every AUD 1 until it is reduced to nil at AUD 150,000. If there is a secondary earner, every AUD of their income above AUD 16,000, reduces the SIFS by AUD 0.15.
The attached calculations assume families are not eligible for the SIFS as the majority of single income families were not eligible for the supplement in 2019-2020.
There were no material changes to the personal income tax system. The Net Medical Expenses Tax Offset, previously available on a grandfathered basis, was abolished from 1 July 2019.
5.1. Changes to labour taxation due to the covid-19 pandemic
A number of temporary changes to income transfers were made by the Australian Government in response to the COVID-19 pandemic during the 2019-2020 year. No changes were made to the personal income tax system during 2019-2020 due to the COVID-19 pandemic.
From 27 April 2020, recipients of a range of income support payments including JobSeeker and Parenting Payment received a taxable supplement of AUD 550 per fortnight (14 day period) for the remainder of the financial year. This supplement is in addition to the standard means-tested income support payment, and the full AUD 550 was paid in each fortnight the recipient qualified for a non-zero amount of income support. This payment was made to eligible recipients for a maximum of 5 fortnights during the 2019-20 financial year, however some continuously eligible recipients received the payment in 4 fortnights depending on their payment date.
Simultaneously, the taper rate for the partner income test for the JobSeeker Payment was temporarily reduced from AUD 0.60 to AUD 0.25 per AUD 1 of income over the income test threshold from 27 April 2020. A number of means tests and waiting periods, including the assets test, were also suspended for most income support payments over this period, and payment eligibility was expanded.
Recipients of a range of income support and income supplement payments, including JobSeeker Payment, Parenting Payment and Family Tax Benefit received a non-taxable one-off Economic Support Payment of AUD 750 in 2019-2020. These one-off payments were predominantly made in April 2020. The Economic Support Payment is included in the Taxing Wages calculations.
From 30 March 2020, the Australian Government also introduced the temporary JobKeeper Payment, a wage subsidy of AUD 1 500 per fortnight. The benefit is paid to employers whose revenue had fallen by 30 per cent (for employers with annual turnover of less than $1 billion), 50 per cent (for employers with annual turnover of more than $1 billion), or 15 per cent (for certain charities). Self-employed individuals were also eligible to receive the JobKeeper payment. While this benefit is paid to employers, it is only paid for employees who had been paid at least AUD 1 500 per fortnight, so it operates in a way that is similar to an income support payment.
6.1. Identification of an average worker
The source of the information used in replying to the questionnaire was the Australian Bureau of Statistics publication Average Weekly Earnings — Australia, catalogue number 6302.0. The survey is now conducted on a biannual basis (it was previously conducted on a quarterly basis up to the June 2012 quarter) and is based on a representative sample of employers in each industry. As a result of this change in frequency, average weekly earnings for the 2019-2020 income tax year have been calculated as the average of the two biannual figures (November 2019 and May 2020 (released in August 2020)).
In August 2009 the Australian Bureau of Statistics (ABS) redesigned the survey and replaced the industry classification based on the 1993 edition of the Australian and New Zealand Standard Industrial Classification (ANZSIC), which had been in use since 1994, with the 2006 edition of ANZSIC. The 2006 edition of ANZSIC was developed to provide a more contemporary industrial classification system, taking into account issues such as changes in the structure and composition of the economy, changing user demands and compatibility with major international classification standards. Accordingly, the average wage figure for 2010 and later years is inconsistent with that provided for previous years.
All wage and salary earners who received pay for the reference period are represented in the Survey of Average Weekly Earnings (AWE), except:
employees of enterprises primarily engaged in agriculture, forestry and fishing;
employees on workers’ compensation who are not paid through the payroll.
Also excluded are the following persons who are not regarded as employees for the purposes of this survey:
casual employees who did not receive pay during the reference period;
employees on leave without pay who did not receive pay during the reference period;
employees on strike, or stood down, who did not receive pay during the reference period;
self-employed persons such as subcontractors, owner/drivers, consultants;
The sample for the AWE survey, like most ABS business surveys, is selected from the ABS Business Register which is primarily based on registrations with the Australian Taxation Office's (ATO) Pay As You Go Withholding (PAYGW) scheme (and prior to 1 June 2000 the Group Employer (GE) scheme). The population is updated quarterly to take account of:
Earnings comprise weekly ordinary time earnings and weekly overtime earnings.
Weekly ordinary time earnings refers to one week’s earnings of employees for the reference period attributable to award, standard or agreed hours of work. It is calculated before taxation and any other deductions (e.g. board and lodging) have been made. Included in ordinary time earnings are award, workplace and enterprise bargaining payments, and other agreed base rates of pay, over award and over agreed payments, penalty payments, shift and other allowances; commissions and retainers; bonuses and similar payments related to the reference period; payments under incentive or piecework; payments under profit sharing schemes normally paid each pay period; payment for leave taken during the reference period; all workers’ compensation payments made through the payroll; and salary payments made to directors. Excluded are overtime payments, retrospective pay, pay in advance, leave loadings, severance, termination and redundancy payments, and other payments not related to the reference period.
Weekly overtime earnings refers to payment for hours in excess of award, standard or agreed hours of work.
6.2. Employers’ contribution to private health and pension scheme
In Australia very few employers make any contributions towards health schemes for their employees, especially where the employee is at a wage level comparable to that of an average production worker.
Employer contributions to pension schemes are primarily through the superannuation system. This is described in section 2.2.
The equations for the Australian system in 2020 are mostly repeated for each individual of a married couple. However, the spouse credit is relevant only to the calculation for the principal earner and the calculation of the Medicare levy uses shading-in rules which depend on the levels of earnings of the spouses. The basis of calculation is shown by the Range indicator in the table below.
The functions which are used in the equations (Taper, MIN, Tax etc) are described in the technical note about tax equations. Variable names are defined in the table of parameters above, within the equations table, or are the standard variables “married” and “children”. A reference to a variable with the affix “_total” indicates the sum of the relevant variable values for the principal and spouse. And the affixes “_princ” and “_spouse” indicate the value for the principal and spouse respectively. Where the calculation for one earner takes into account variables for the other earner, the affix "_oth" is used. Equations for a single person are as shown for the principal, with “_spouse” values taken as 0.