How Plenence works things out

1. The rules dataset

Every tax band, allowance and threshold lives in a versioned table, each row linked to its official source (GOV.UK, HMRC, DWP, HM Treasury, the FCA Handbook, legislation.gov.uk, FSCS or the Bank of England) with the exact text it was read from. Only validated versions are used. A daily job reads each GOV.UK source through the GOV.UK Content API; when a page changes, a draft version and a review item are created, and a person checks it before a new version is published. Only published versions change anyone's plan. Browse the rules.

2. Who does the maths

Deterministic code. The retirement projection, tax, National Insurance, pension relief, annual allowance and inheritance tax calculations are ordinary functions tested against hand-worked examples. AI is used only to read your documents, to word answers, and to check answers stay on the guidance side. Every figure is calculated by deterministic code from the cited rules.

When Ask Plenence answers a question, every figure in the answer must appear in a calculation result it was given; an answer containing a figure nobody calculated is not shown.

3. The retirement projection

• Annual steps from today to age 100, in today's money. Growth is the FCA COBS 13 Annex 2 intermediate rate (pensions and ISAs 5%, other investments 4.5%), less charges, deflated by the Bank of England's 2% CPI target. Cash keeps pace with inflation.
• Contributions continue until each person's retirement age. Spending starts when the last person retires.
• Income comes first from State Pension (from State Pension age under the DWP timetable) and defined benefit pensions, then from cash, ISAs, other investments and finally pensions, from the normal minimum pension age in force on the date each person reaches it.
• 25% of each pension withdrawal is tax-free until the lump sum allowance is used; the rest is taxed with other income using the cited bands.
• Sustainable income is the highest after-tax income that lasts to 100. The contribution needed is the extra gross monthly pension saving that makes your target last to 100.

4. Monte Carlo probability of success

1,000 paths with a fixed seed, so the same plan gives the same answer. Each year draws a lognormal return around the deterministic real return, with annual volatility of 12% for invested wrappers (treated as moving together) and 1% for cash. These volatilities are Plenence's assumptions, not regulatory figures. We also show how often plans succeed when the first five years of retirement have the weakest returns (sequence-of-returns risk).

5. Inheritance tax

The estate is assets less debts, plus unused defined-contribution pensions when the date of death is on or after 6 April 2027. The nil-rate band (with any transferred share) is used first by gifts in the 7 years before death, in date order, after annual exemptions; the rest of the band and the residence nil-rate band (tapered £1 for every £2 above £2 million, capped at the home passing to direct descendants) apply to the estate. Spouse and charity gifts are exempt; 10% or more to charity lowers the rate to 36%. Trusts and business or agricultural relief are not modelled.

6. Health score

A weighted sum of four measures, each scored 0 to 1:

7. How decisions are ranked

Rank = estimated £ effect × urgency × confidence. Urgency is 3 within 30 days of a deadline, 2 within 90, 1.5 within a year and 1 otherwise. Confidence is 1 for confirmed facts, at most 0.6 for unconfirmed ones, and 0.7× when a balance is more than a year old. Items without a £ estimate (for example stale data) use a £250 floor so they appear below money decisions. Every decision shows its facts, rules, assumptions and alternatives.

8. The advice boundary

Plenence is not authorised by the Financial Conduct Authority. It gives guidance and modelling, not regulated financial advice. For free impartial guidance, use MoneyHelper or, if you are 50 or over with a defined contribution pension, Pension Wise.

Every Ask Plenence answer goes to a separate classifier that scores it from 0 (facts) to 5 (executing a transaction). Answers at 4 or above (a specific product, fund, provider or transfer recommendation) are rewritten as guidance and checked again; if they still cross the line, or the check itself fails, the answer is withheld. Decisions in your plan are written in advance at level 3 or below. When a recommendation is asked for, Plenence says:

“I can explain the trade-offs and model the financial impact, but I can't give a personal recommendation about a specific product, fund, provider or transaction. Plenence is not authorised by the FCA to do that.”

9. Your documents

Uploads are encrypted (AES-256-GCM) before they are stored, and read by a language model through OpenRouter routed only to providers that neither train on nor retain the data. Extracted figures start unconfirmed and show the page and words they came from. Deleting a document deletes its unconfirmed figures; deleting your account deletes everything.