Why this calculator exists
Several family-finance rules depend on adjusted net income but use different boundaries and consequences. HICBC begins over £60,000 and reaches 100% at £80,000. At £100,000, the Personal Allowance starts to taper and the income condition for Tax-Free Childcare and England’s Free Childcare for Working Parents becomes especially important. Seeing these on one income line can make the interaction easier to understand.
The calculator is an educational utility, not an optimiser. It shows the estimated adjusted net incomes of both partners, identifies the higher figure for the HICBC estimate and reports the distance to each major threshold. It also explains how relief-at-source pensions, gross contributions, salary sacrifice, net-pay pensions and Gift Aid are treated so that a reduction is not accidentally counted twice.
An official-source-first method
The rule file links directly to GOV.UK and HMRC material for adjusted net income, Income Tax rates and Personal Allowance, HICBC, Child Benefit rates, Tax-Free Childcare and Free Childcare for Working Parents. A Department for Education publication supports the historical childcare rollout note, and the Scottish Income Tax page supports the warning that a 40% taper-effect estimate is not a Scottish tax calculation.
Unofficial tax blogs are not used as source of truth. Commentary pages may explain the arithmetic in plainer language, but the versioned numbers come from the official-source table. The visible last-checked date is 20 June 2026. Each tax year stores its own Child Benefit rates and dates so a future update can change one version without silently rewriting the previous year.
Transparent calculation choices
The HICBC estimate uses complete £200 steps above £60,000, capped at 100%. Annual Child Benefit is weekly rate multiplied by 52 and labelled an estimate. Personal Allowance is reduced by £1 for every £2 of adjusted net income over £100,000 and reaches zero at £125,140. The rough tax effect multiplies lost allowance by 40% for England, Wales and Northern Ireland only.
Childcare statuses have three states: within, at threshold and over. Exactly £100,000 is never labelled over. An over result means the £100,000 income condition is likely not met; a within result means only that this income condition appears satisfied. The tool does not collapse work, minimum earnings, child age, approved-provider, immigration and reconfirmation rules into a false yes-or-no entitlement promise.
Privacy by design
All calculator arithmetic runs in the browser. Income, pension, Gift Aid, child-age and childcare-spending values are held only in the page’s current memory and are not sent to an application database. Reloading the page clears the entries. The copy button writes the generated summary to the device clipboard only when the user asks, and printing uses the browser’s own print function.
The application does not require an account and does not include advertising trackers in the MVP. External official links leave this website and are governed by the destination’s privacy and cookie policies. A deployment platform may keep ordinary request and security logs, but calculator form values are not placed in URLs, server requests or analytics events by this codebase.
What the calculator deliberately does not cover
It is not a full tax-return or take-home-pay calculator. Self-employed people may need final profits, company benefits can affect taxable income, foreign income may require specialist analysis and losses or unusual reliefs can change HMRC’s calculation. It does not calculate pension annual allowance, validate Gift Aid, determine residence, price provider extras or allocate an uneven childcare bill between children and quarters.
The England working-parent childcare result does not apply to Scotland, Wales or Northern Ireland. The 2025/26 tax year crossed a change in England’s offer, so the website shows a transition warning instead of one annual-hours figure. Exact Child Benefit and HICBC can also differ when entitlement starts or stops during the year. These limitations are visible rather than hidden in fine print.
How the site is maintained
Rules are held in a versioned TypeScript data file with source URLs and a checked date. Pure calculation functions are kept separate from the user interface and covered by unit tests, including every requested HICBC boundary, Child Benefit examples, Personal Allowance points, childcare status at £100,000 and £100,001, and both salary-sacrifice input treatments.
An update should begin with the official source ledger, not a code edit. New rates are added as a new tax-year object, expected boundary examples are updated or extended, and the test suite must pass before publication. The update log records the checked date and material rule changes. If an official rule is unclear or region-specific, the preferred behaviour is to show that uncertainty rather than infer a convenient answer.
Check the numbers with the full calculator
Compare both partners, pension methods, Gift Aid, Child Benefit, childcare income limits and the Personal Allowance taper in one place.
Open the calculator