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Retire the carry-forward spreadsheet.

The UK adviser calculator your compliance officer will sign without comment — including the post-2021/22 top-slicing rule HMRC's own tool still gets wrong.

Drop in the P60, the pension annual statements, the chargeable-event certificate. ParaplanAI extracts the figures, surfaces every assumption for your review, runs the statutory calculation, and produces a typeset working — reproducible six years later under exactly the inputs that produced it.

Run 3 free calcsSee a worked example  →

3 free calcs / month · no card required

§ 01The problem

The same calculation, three different answers.

“Three to four hours per case in a master spreadsheet — and it gave the wrong answer the year the threshold moved. Quietly, on every case afterwards.”

  • — 01

    Statutory inputs change every year.

    AA was £40k, then £60k. The taper threshold moved twice. MPAA was £4k, then £10k. The maths quietly drifts.

  • — 02

    Documents arrive in nine formats.

    P60s, P11Ds, pension annual statements, chargeable-event certificates. Each one is keyed in by hand.

  • — 03

    The output isn’t fit to send.

    A spreadsheet print-out is for the file, not the client. It’s unreviewable — and impossible to audit six months later.

“Errors still exist in HMRC's tax calculations.”

AccountingWEB →·Tax Adviser Magazine: Learn to slice correctly →

HMRC Brief 12/2021 changed top-slicing relief — for gains from 6 April 2021, the personal-savings allowance and starting-rate band are recalculated at notional income, not carried from the main calc. The published tool, and most commercial software written to its spec, never updated. The result is misstated tax — sometimes by tens of thousands.

ParaplanAI applies the post-2021/22 rule by default. Every step of the PSA recalculation is on the page. Every output is replayable twelve months later against exactly the inputs and tax-year config that produced it. The kind of working a compliance officer will sign without comment.

Read the full audit case  →
§ 02What it does

Document in. Working out.

ParaplanAI reads the documents, surfaces every extracted figure for your review before it's used, runs the calculation against HMRC-verified statutory rules for the relevant tax year, and produces a typeset working that links each figure back to its source. Nothing is invented. Everything is reproducible.

  • 01

    Pension contribution analysis.

    Personal, employer, salary-sacrifice and relief-at-source contributions reconciled against the pension input period and tax year.

  • 02

    Annual allowance & taper.

    Threshold and adjusted income to HMRC definitions. Taper applied with the correct floor for the year — including high-income individuals.

  • 03

    Carry forward over three years.

    Unused allowance applied chronologically with explicit checks on scheme membership for each year drawn from. MPAA-aware where triggered.

  • 04

    Bond gains & top-slicing.

    Chargeable-event gains by policy with the slice computed correctly — including the post-2021/22 PSA recalculation that quietly catches everyone out.

§ 03The method

Document to signed report, in four steps.

  1. — 01

    Drop the documents.

    P60, P11D, pension annual statements, chargeable-event certificate. ParaplanAI reads each one, surfaces what it found, and asks for a yes before using it.
  2. — 02

    Confirm the assumptions.

    Tax year, pension input period, scheme membership for each carry-forward year, salary-sacrifice arrangement, MPAA status. Every assumption on screen, named, editable.
  3. — 03

    Read the working.

    A single number — the available allowance, the chargeable gain, the top-sliced liability — with every step that produced it. Exportable as PDF, ready to attach to the suitability letter.
  4. — 04

    Sign & archive.

    The scenario is timestamped, attached to the client record, and reproducible six years later under exactly the inputs that produced it.
§ 04A specimen

Not a dashboard. A document.

Calculator · 04 / 12

Carry forward, tapered. Mr Hartley earns £284k and contributed £72k across personal and employer in 2025/26. The available allowance is more interesting than the headline taper — and only carry-forward gets it right.

Specimen · Carry-forward calculator

Available allowance, 2025/26

Ref   AC·CF·2026/04
Client   Hartley, R. & J.
Tax year   2025/26
Inputs
Threshold income
£218,400
Adjusted income
£284,200
Personal contribution
£48,000
Employer contribution
£24,000
MPAA in scope
—
Working
  1. 01Threshold income£218,400
  2. 02Adjusted income£284,200
  3. 03Taper applied−£32,900
  4. 04Tapered AA, 2025/26£27,100
  5. 05Carry-forward, 3 prior yrs£34,000
Maximum available
£61,100

Tapered AA £27,100 plus carry-forward £34,000 from the three preceding tax years. Drawing on 2022/23 (£16k) and 2023/24 (£18k); 2024/25 unused.

Tapered AA, 2025/26
£27,100
Carry forward, 2022/23
£16,000
Carry forward, 2023/24
£18,000
Method   HMRC PTM 057100Engine   v1.0 · 2025/26Hash   7d3a·9e1c
Calculator · 09 / 12

Top-slicing, recalculated. Mr Okonkwo full-surrenders an offshore bond for an £88,800 gain. The top-sliced liability after the 2021/22 personal-allowance restoration runs to £3,330 — and only the post-Brief-12 method gets it right.

Specimen · Bond chargeable-event calculator

Top-sliced liability

Ref   AC·BG·2026/09
Client   Okonkwo, A.
Event   Full surrender
Sliced gain by year
2020/21£12,200
2021/22£13,400
2022/23£14,100
2023/24£14,800
2024/25£16,100
2025/26£18,200

Slices in teal exceed the basic-rate band at notional income — and so attract additional liability after the 2021/22 personal-allowance restoration step.

Net liability after relief
£3,330

Onshore policy — 20% deemed credit applied. Full-surrender event, six insurance years, Brief 12/2021 PSA recalculation at notional income.

Chargeable gain
£88,800
Tax credit, basic rate
£17,760
Top-slicing relief
£8,440
Method   HMRC IPTM 3820 + Brief 12/2021Engine   v1.0 · 2025/26Hash   4f12·a8e2
§ 05Plans

Two paid tiers. Same engine.

Freetry first

Three calculations a month so you can run a real case before paying.

£0/ month
  • One adviser seat
  • Pension AA + carry-forward + MPAA
  • Bond chargeable gain + top-slicing
  • 3 calculations / month
  • Compliance annex PDF
  • 6-year audit retention
Run 3 free calcs
Prorecommended

The sole practitioner. Unlimited calcs, branded PDFs, full audit trail.

£39/ month
  • One adviser seat
  • Unlimited calculations
  • Branded PDFs (firm logo + colour)
  • 100 document extractions / month
  • Save-as-draft workflow
  • 6-year audit retention
Run 3 free calcs
Firmmulti-adviser

Shared client roster, paraplanner drafts → adviser sign-off, unlimited everything.

£69/ month
  • Unlimited adviser seats
  • Everything in Pro
  • Shared client + case roster
  • Paraplanner draft → adviser sign-off
  • 500 document extractions / month
  • Priority support
Run 3 free calcs

Prices shown ex-VAT. UK 20% VAT applies on top. Subscriptions can be paused, downgraded, or cancelled any time from firm settings.

§ 06Questions

The questions we get asked.

No. The AI extracts figures from documents — the P60 salary, the PSS contributions, the chargeable-event certificate gain. Every extracted figure is shown for review before the calculation runs. The maths is deterministic TypeScript verified against HMRC's PTM and IPTM corpora to zero pence tolerance. The two layers never mix.
Stored in UK-region object storage, encrypted at rest, scoped to your firm by row-level security. Default retention is 30 days; PDFs are auto-purged after that. Your firm is the data controller; we're joint processor under a standard UK-GDPR DPA.
Yes. Every calc run persists the full inputs, the tax-year config version, and every intermediate step. The replay produces the same answer to the penny.
Yes. HMRC Brief 12/2021 mandates that PSA and SRB are recalculated at notional income level in Step 4 of the top-slicing relief calculation, not carried over from Step 3. This is the load-bearing differentiator versus DIY templates — and the bug we most often find when reviewing a firm's existing spreadsheet.
Not in v1. The current engine applies the rUK rates and notes this on the working. Scottish bands are planned for v2 — let us know if it's a hard blocker for your firm.
No. ParaplanAI illustrates and calculates; it doesn't recommend. Every output is marked For planning and illustration purposes only. This tool does not constitute financial or tax advice. The adviser remains responsible for suitability.
30 days · no card

Stop maintaining the spreadsheet.

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