UK Tax Year and Week Helper

Batch date-only UK tax year, tax week and tax month labels and inclusive boundaries.

Inputs and calculation

Supply date as YYYY-MM-DD, from 2020-04-06 through 2027-04-05. Only calendar classification is provided; do not submit employee or taxpayer information.

The UK tax year runs from 6 April through 5 April.2 Tax weeks start with 6–12 April; the remaining one or two days after 52 complete weeks form week 53. Tax months run from the sixth through the fifth of the next month.1

Each row returns taxYear as YYYY/YY, yearStart, yearEnd, taxWeek, weekStart, weekEnd, taxMonth, monthStart, monthEnd, and one-based dayOfTaxYear. All endpoints are inclusive. The week is a tax-calendar label, not an ISO week and not proof that a payroll requires an extra payment or allowance.

This uses the cited calendar definitions throughout the supported range. No Income Tax, National Insurance, statutory pay, payment schedule, filing deadline or payroll deduction is calculated. Dates outside the fixed range are rejected; extending the supported range requires a reviewed release. Not legal or tax advice.

Example

{
  "items": [
    {
      "date": "2026-04-05"
    }
  ]
}

The dataset and local CLI return these rows:

[
  {
    "rowIndex": 0,
    "date": "2026-04-05",
    "taxYear": "2025/26",
    "yearStart": "2025-04-06",
    "yearEnd": "2026-04-05",
    "taxWeek": 53,
    "weekStart": "2026-04-05",
    "weekEnd": "2026-04-05",
    "taxMonth": 12,
    "monthStart": "2026-03-06",
    "monthEnd": "2026-04-05",
    "dayOfTaxYear": 365
  }
]

Batch and output behaviour

Supply 1–10,000 items. Unknown fields are rejected. Validation finishes for the whole batch before storage or billing. One invalid row fails the run with its zero-based index; input values are not included in the error. Duplicate rows are preserved and each stored row counts as a result. rowIndex preserves input order.

The Apify dataset holds results. The key-value store record OUTPUT contains requestedCount, storedCount, truncated and results. A configured charge limit may shorten the dataset; OUTPUT includes only those saved rows. Start a fresh run after an interruption: a non-empty dataset is rejected to prevent duplicate billing. Storage and billing are not a single transaction; infrastructure failures can leave partial storage or a charge requiring platform review.

Local use and tests

node cli.js examples/input.json
node tests/run.js

These commands need only Node and use no network or SDK installation. The deployment target is Node 22. main.js uses the Apify SDK for platform storage and billing. The container installs the declared dependency during a future build.

Pricing suggestion

Suggested pay-per-event price: $1 per 1,000 stored results ($0.001 per result-item event). No custom start fee. This is a proposed configuration, not active pricing. The manager must configure the exact event name and price in Apify before any release. The SDK call uses Actor.pushData(results, "result-item"); do not also add a separate charge for those rows. Apify billing documentation (accessed 2026-10-03).

Sources and data licences

Contains public sector information licensed under the Open Government Licence v3.0. GOV.UK makes its content available under OGL except where stated otherwise; see the numbered GOV.UK terms source below. Licence: https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. No external data is fetched at runtime.

1. HMRC employer guide 2026 to 2027: tax weeks and months — accessed 2026-10-03. Open Government Licence v3.0.
2. GOV.UK tax year definition — accessed 2026-10-03. Open Government Licence v3.0.
3. GOV.UK terms and conditions — accessed 2026-10-03. Open Government Licence v3.0.

AI-generated software draft for LandlordTools; manager review required before release.