Data Sources

Every figure in Selvox comes from a named, citable source

We believe you should be able to trace every number in Selvox\u2019s calculations back to its source. This page lists every data source we use, with links, date coverage, and update frequency.

Primary Sources

Barclays Equity Gilt Study

ProviderBarclays plc

Coverage1899 to present (updated annually)

Used forUK equity total returns, UK gilt total returns, UK cash returns, RPI inflation — the primary return series for the Monte Carlo simulation

UpdatedAnnual (typically February/March)

CostApproximately £150 per edition

The definitive long-run UK asset return dataset. Includes both World Wars, the Great Depression, the 1970s stagflation, Black Monday, the dot-com crash, the 2008 financial crisis, and COVID-19. Selvox updates the return series annually after each new edition is published.

ONS Consumer Price Indices

ProviderOffice for National Statistics

CoverageCPIH from 1988, CPI from 1989, RPI from 1947

Used forInflation adjustment in simulations, State Pension triple lock modelling

UpdatedMonthly

CostFree

Official UK inflation statistics. We use CPIH as the primary series for recent years and RPI for historical periods where CPIH is unavailable.

JST Macrohistory Database

ProviderJordà-Schularick-Taylor

Coverage1870 to present, multiple countries including UK

Used forSurvivorship bias correction cross-validation, independent check on UK equity return series

UpdatedPeriodic (major updates every few years)

CostFree (academic dataset)

Academic dataset covering 18 advanced economies. Citation: Jordà, Ò., Knoll, K., Kuvshinov, D., Schularick, M., and Taylor, A.M. (2019). “The Rate of Return on Everything, 1870–2015.” Quarterly Journal of Economics, 134(3), 1225–1298.

HMRC Tax Rates and Allowances

ProviderHM Revenue & Customs

CoverageCurrent tax year (2026/27)

Used forIncome tax bands, NI thresholds, CGT rates, dividend tax rates, ISA and pension allowances

UpdatedUpdated after every UK Budget

CostFree

Selvox's tax engine is updated within 48 hours of every Budget announcement.

Scottish Government Tax Rates

ProviderScottish Government / Revenue Scotland

CoverageCurrent tax year (2026/27)

Used forScottish income tax bands (Starter 19%, Basic 20%, Intermediate 21%, Higher 42%, Advanced 45%, Top 48%) applied when Scotland is selected as country of residence

UpdatedAnnual (Scottish Budget, typically December)

CostFree

Scottish income tax applies to non-savings, non-dividend income only. NI, CGT, and dividend tax remain reserved to Westminster.

DWP State Pension Data

ProviderDepartment for Work and Pensions

CoverageCurrent rules (2026/27)

Used forFull new State Pension weekly rate (£241.30), qualifying years requirement (35), deferral uplift rate (5.8% per year)

UpdatedAnnual (April uprating)

CostFree

PLSA Retirement Living Standards

ProviderPensions and Lifetime Savings Association

Coverage2024 (updated annually)

Used forBenchmark spending levels shown in Step 5 of the calculator wizard (Minimum £14,400, Moderate £31,300, Comfortable £43,100 for single person)

UpdatedAnnual

CostFree

Update Schedule

Selvox is only as accurate as its source data. We maintain a schedule for updating each source as new data is published:

Source	Last updated in Selvox	Next update due
Barclays EGS	On publication	Feb/Mar 2027
ONS Inflation	Ongoing	Monthly
HMRC Tax Rates	Spring Budget 2025	After next Budget
Scottish Government	Scottish Budget 2025	Scottish Budget 2026
DWP State Pension	April 2026	April 2027
PLSA Standards	2024 update	Annual

Found a data issue?

If you believe a figure in Selvox is using outdated or incorrect source data, please email hello@selvox.co.uk with a reference to the source and the discrepancy. We treat data accuracy reports as high-priority.