A Midlands drinks bottler filing one quarter of UK Plastic Packaging Tax owes £1,928.46 — and £3,268.46 if the return is three weeks late. Both numbers come out of the same eight inputs, in one click, in a browser tab.
Here is the part that catches people. On 1 April 2026 HMRC uprated Plastic Packaging Tax to £228.82 per tonne, from £223.69. Ask a chatbot this week and it will almost certainly give you £223.69, because that is the number sitting in most of the text it learned from. On the worked example above that stale figure produces £1,885.23 instead of £1,928.46 — £43.23 of wrong tax on one quarter, from one number nobody re-checked.
Plastic Packaging Tax 2026-27 Check is a browser extension, plus a free web page running the identical code, that turns the quarter into eight fields.
You type: finished plastic packaging manufactured in or imported into the UK over the rolling twelve months; how much of that was exempt or excluded, such as transport packaging or licensed human medicine; the tonnage in the period you are filing; the share of that tonnage in components at 30% or more recycled plastic; your period end; days already past the deadline; whether you are registered; and which rate year applies.
Take the defaults it ships with: 42 tonnes over the year, 1.5 tonnes exempt, 11.5 tonnes in the period ending 30 September 2026, 24% of that clearing the recycled threshold, twenty-one days late, not yet registered.
Registration status: over 10 t and not registered, so register within 30 days. Tonnage counted toward the threshold: 40.5 t — exempt stock comes off first, which is where hand calculations go wrong. Chargeable tonnage: 8.428 t, because only the share below 30% recycled plastic is charged, not a company-wide average. Rate applied: £228.82 per tonne. Tax due: £1,928.46.
Then the clock. The penalty for missing a relevant requirement is a fixed £500, then £40 for every day until it is met. At twenty-one days that is £1,340, added straight onto the tax: total exposure £3,268.46. The last output is the one people get wrong most cheaply. Your return and payment are due no later than the last working day of the month after your accounting period ends. For the quarter ending 30 September 2026 that is Friday 30 October 2026 — not the 31st, because 31 October 2026 is a Saturday. Change the period end to 31 December 2026 and the tool returns Friday 29 January 2027, for the same reason: 31 January 2027 is a Sunday. A diary reminder set for month end is a reminder set after the deadline.
Why not just read GOV.UK? You should, and the README cites it. But HMRC's guidance gives rules, not a figure. It will not net off your exempt tonnage, split your recycled-content test, run the daily penalty, or tell you which weekday the deadline lands on. A UK tax adviser will do all of that and bill £75 to £250 an hour, and a registration-and-return review is rarely under two hours.
Every calculation is free, in the popup and on the web page, with no key, no watermark and no cap. The free tier answers the whole question and stops. The $60 licence key adds ownership and repetition: CSV export of each quarter's eight figures, so the working becomes a file you keep for HMRC evidence, and a browser alarm 30, 14 and 1 days before the due date. $60 once, one key per person or team seat, seven-day full refund. The key never blocks an answer.
It is a calculator, not tax advice. Check the figures against your records before you file — but check them against a rate from this April, not last.
Free in your browser (the same rules): https://getreadystack.com/tools/plastic-packaging-tax-2026-check
Licence ($60, once, 7-day refund): https://buy.polar.sh/polar_cl_PYbBrJJkoluCNMbyvGNB7XIkrfUw60XeeZ8wH4e6Zf8
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