Our Methodology

Primary data sources

ONS Annual Survey of Hours and Earnings (ASHE)

Our core salary data comes from the ONS Annual Survey of Hours and Earnings, accessed via the NOMIS API (dataset NM_99_1). ASHE is the most comprehensive source of earnings data in the UK, based on a 1% sample of employee jobs from HMRC PAYE records — covering approximately 300,000 jobs each year.

We use ASHE Table 14.7a (gross annual pay for all employees) and Table 14.5a (full-time employees only), broken down by Standard Occupational Classification (SOC) code at the 4-digit level. This gives us median, mean, and percentile (P10, P25, P75, P90) salary figures for each of the 520 occupation categories.

ASHE data has known limitations: it excludes self-employed workers, covers only those on PAYE, and may suppress figures for occupations with small sample sizes to protect statistical confidentiality. Where data is suppressed, we indicate this clearly on occupation pages.

HMRC Longitudinal Education Outcomes (LEO)

For postgraduate and degree outcomes data, we use HMRC LEO tax records, which track the earnings of UK graduates at 1, 3, 5 and 10 years after graduation. This dataset links university records with HMRC tax data, providing actual earnings figures (not survey responses) for graduates by degree subject and institution.

LEO data is published annually by the Department for Education and covers graduates from English higher education institutions. It captures employed graduates' earnings through the tax system, providing a more reliable picture than self-reported survey data.

Occupation classification

All occupation data uses the ONS Standard Occupational Classification (SOC) system, which categorises jobs based on skill level and skill content. We use the 2020 SOC revision, which defines occupations at four levels of detail:

• Major groups (1 digit) — 9 broad categories such as "Professional occupations" or "Skilled trades"
• Sub-major groups (2 digits) — 26 categories providing more specific groupings
• Minor groups (3 digits) — 104 categories
• Unit groups (4 digits) — 412 detailed occupation categories (our primary level of analysis)

We display occupation pages at the 4-digit (unit group) level, which provides the most specific salary data available from ASHE while maintaining statistical reliability.

Career progression models

The career path salary trajectories shown on our career pages are modelled based on typical UK industry timelines, informed by:

• ONS SOC occupation-level data for entry, mid-career and senior roles within each career path
• Industry salary surveys and professional body benchmarking data
• Published career progression frameworks from relevant professional bodies

Career path stages (entry, mid-career, senior, leadership) represent typical progression timelines. Actual individual progression varies based on employer, location, qualifications, performance and market conditions.

Regional salary adjustments

Regional salary data uses ONS regional pay differentials derived from ASHE. Our regional multipliers are calculated from the ratio of regional median full-time earnings to the national median, using the most recent available ASHE data.

These multipliers are applied uniformly across career stages within each region. In practice, regional variation may differ by seniority level and occupation — for example, London premiums tend to be larger for senior roles than for entry-level positions.

Gender pay gap data

Gender pay gap figures on occupation pages are calculated directly from ASHE data, comparing male and female median annual earnings for the same SOC code. The gap is expressed as a percentage: (male median - female median) / male median × 100.

This measures the difference in pay between men and women in the same occupation category. It does not control for differences in working patterns, seniority levels, or other factors within the occupation category.

Inflation adjustments

Where we show real (inflation-adjusted) salary trends, we use the ONS Consumer Prices Index including owner occupiers' housing costs (CPIH) as the deflator. Nominal figures are adjusted to the most recent year's prices.

Data currency and updates

ASHE data is published annually, typically in October/November for the preceding April survey period. We update our dataset within two weeks of each new ASHE release. The data year shown on occupation pages indicates the ASHE survey year (e.g., "2025" means the April 2025 survey, published in late 2025).

LEO data is published annually by the Department for Education, typically in the summer. We update postgraduate outcomes data following each release.

Limitations and caveats

• ASHE covers employees on PAYE only — self-employed workers are excluded, which particularly affects occupations with high self-employment rates (e.g., construction trades, creative industries)
• Small sample sizes in some occupations may lead to volatile or suppressed figures
• Career progression models represent typical paths and may not reflect individual circumstances
• Regional multipliers are uniform across occupations — actual regional variation differs by role
• Gender pay gap figures do not control for differences in hours, seniority or other factors within occupation categories
• All salary figures are gross annual pay before tax and deductions

Licensing

ONS data used on this site is published under the Open Government Licence v3.0. Source: Office for National Statistics — Annual Survey of Hours and Earnings.

LEO data is published by the Department for Education under the same licence.

Questions about our data?

If you have questions about our methodology, data sources, or how we present salary information, please get in touch. We're committed to transparency and accuracy in everything we publish.