For financial advisors
The projection engine behind plannng - available for your platform.
We built a retirement cashflow engine that models income, pensions, tax, and drawdown year by year. It powers the consumer app. Now we're making it available to financial advisors and wealth managers who want the same depth in their own tools.
What the engine does
Year-by-year cashflow projections
Models income, expenses, pensions, ISAs, GIAs, and state pension across the full lifetime. Handles accumulation and decumulation with real tax calculations - not approximations.
Monte Carlo stress testing
Runs hundreds of market return sequences to give a probability-based outcome - not just a single deterministic line. Show clients the range of what could happen, not just the best case.
Full UK tax model
Income tax, National Insurance, pension tax relief, annual and lifetime allowances, dividend tax, capital gains - calculated year by year using current HMRC rules, with the ability to model future changes.
Couples modelling
Joint plans that account for two separate tax positions, different retirement ages, survivor income needs, and combined household expenses.
Scenario comparison
Change any input - retirement age, contribution rate, drawdown strategy - and instantly see how the outcome shifts. Let clients explore trade-offs in real time during meetings.
Under the hood
The engine runs a full month-by-month simulation of your client's financial life. Here's what's happening at each layer.
Projection modes
Deterministic projection
A single, clear trajectory using fixed assumptions. Shows clients the expected path if markets deliver the assumed return year after year.
Month-by-month engine covering up to 840 months (70 years). Fixed growth rates applied per element.
Monte Carlo simulation
Runs hundreds of randomised market scenarios to show the range of outcomes and the probability of success - not just the best case.
N stochastic simulations with normally-distributed monthly returns around configured growth rates. Aggregated into P10/P25/P50/P75/P90 bands. Async job submission for long-running runs.
What happens each month
Every projected month executes four phases in sequence. This is the core simulation loop.
Growth and contributions
Apply investment growth and add regular contributions to each active pot.
Percentage or absolute growth, monthly or annual frequency. Compound conversion applied internally.
Liquidation and pension crystallisation
Process any scheduled lump-sum events - pension tax-free cash, planned withdrawals, or full crystallisation.
PCLS capped at 25% with Lifetime Savings Allowance tracking. Supports both drawdown and UFPLS crystallisation paths.
Income, expenses, and tax
Aggregate all income and expenses for each person, calculate the tax due, then cover any shortfall from surplus cash before triggering drawdowns.
Full income tax calculation using rUK or Scottish bands. Shortfalls absorbed by a synthetic Cash Pot that accumulates surpluses across months.
Drawdown
If expenses still exceed net income, draw from investments and pensions in the priority order you set - spreading evenly across same-priority pots.
Tax-aware grossing-up for pension and GIA withdrawals. Fair distribution across equal-priority elements.
Plan elements
Everything in a client's financial picture maps to one of five element types.
Income
Employment, rental, or other income with start and end dates.
Expense
Living costs, bills, and other outgoings.
Investment
ISA (tax-free), GIA (capital gains taxed), or Savings (interest taxed via PSA).
Pension
PCLS drawdown (25% tax-free + taxable income) or UFPLS withdrawal.
Asset
Non-income holdings like property or vehicles - tracked for net worth but not drawn down.
Tax model
Full UK tax calculation, every year
Not estimates or flat-rate assumptions. The engine calculates actual tax liability using current HMRC bands, allowances, and thresholds - updated as rules change.
Personal allowance tapering, basic/higher/additional rate bands, Scottish variant bands, CGT annual exemption, Personal Savings Allowance, and LSA tracking. Tax years run April to March.
Other capabilities
Why this exists
Built from the inside
Most cashflow tools treat tax as an afterthought or require advisors to maintain their own assumptions. We built the engine to handle the full complexity of UK retirement planning - pensions, tax, drawdown ordering, inflation - so you don't have to build it yourself.
How to get started
Tell us what you're building
Whether you want to embed projections in an existing platform, build a client-facing tool, or power your back-office planning - we'll scope what the engine needs to do for you.
We set up access
API credentials, documentation, and a sandbox environment so your team can integrate and test against real calculations.
Go live
Production access with ongoing support. Tax rules stay current. The engine improves continuously - your integration benefits automatically.
business@plannng.co