Civic Ledger a country through generations
Begin with ten million people, then decide who works, earns, pays, needs support, has children and arrives each year. Civic Ledger carries those assumptions through births, ageing, public services, borrowing and interest. It does not tell you what to believe. It shows exactly what must be assumed for a conclusion to follow.
Choose an intervention above, then click any population block. The selected cohort's visible assumptions and the dashed year-80 future will change immediately.
Nothing changes invisibly: every intervention also moves the matching advanced sliders.This is the deliberately extreme case
The opening preset encodes rapid inflow alongside unusually low employment and compliance, high support use, large families and heavy justice demand. It is a proposition to test, not evidence that such a population exists.
A national argument turned into inspectable arithmetic
Public debates often leap from a group label to a future. Civic Ledger removes that shortcut. Established households, new-arrival households and locally born descendants occupy separate accounts, but the names never enter an equation. Employment, earnings, tax compliance, support take-up, fertility and justice-system demand do. Give two cohorts the same numbers and they produce the same fiscal result.
People move through time
Four age bands advance annually. Births, age-specific mortality and new arrivals obey one stock-flow identity.
Work creates the base
Employment, earnings and compliance determine taxable output. Children, retirement and non-employment change dependency.
Claims meet revenue
Support, pensions, justice and public services compete with interest for tax receipts and limited new credit.
Shortfalls feed back
Unfunded infrastructure slows productivity. Debt raises interest; exhausted lender headroom forces obligations and services to be rationed.
What the five scenarios teach
- Extreme stress test: expresses the severe hypothetical in the brief. Find the year cash support approaches tax revenue and inspect what actually causes the break.
- Balanced continuity: holds migration positive but makes the two adult profiles broadly similar. This isolates the effect of the assumed behaviour.
- High-contribution inflow: raises entrant employment and earnings. The same arrival mechanism can expand the workforce, repay debt and support an ageing host population.
- Integration dividend: begins with weak first-generation outcomes while descendants converge strongly. Its early squeeze can turn into recovery.
- Closed ageing country: removes migration altogether while fertility remains low. A shrinking workforce can create a different route to pension and service pressure.
A transparent cohort projection; labour income tax; household support; pensions; age-weighted services; justice cost; debt, interest and a simplified external-credit ceiling.
Trade, housing prices, capital taxes, business formation, remittances, emigration, behavioural responses to policy, unequal households, actual crime data and political decision-making.
Fixed mechanics that are not sliders
Ageing and mortality. Age bands last 18, 22 and 25 years before 65+. Annual mortality is 0.04%, 0.12%, 0.6% and 4.5%. Births use half of adults aged 18–39 across a 22-year fertility window.
Arrival shape. Every annual inflow is 18% children, 62% aged 18–39, 17% aged 40–64 and 3% aged 65+. Children arriving from abroad enter the descendant profile when they become adults.
Unit claims. Generic annual units are 16,000 per supported adult, 6,000 per supported child, 18,500 per pensioner, 25,000 per justice incident and 5,200 per resident before age weighting.
Credit rule. Interest rises five percentage points for each 100% of GDP that debt exceeds 65%, capped at 24%. Cash pays interest, mandatory claims, then services; unpaid interest is capitalised.
Living-standard index. Year zero equals 100. Later values combine disposable resources per person (55%), funded services (30%) and the inverse justice-demand load (15%), capped at 180.
Method, evidence and limits
The population side follows the logic of the United Nations' cohort-component method: advance age groups while separately accounting for fertility, mortality and migration. The fiscal side follows the stock-flow distinction emphasised in the OECD's long-term projection framework: employment drives government finances while many expenditures follow the total population and its age structure.
This lab intentionally contains no empirical nationality preset. The UK's independent Migration Advisory Committee likewise models fiscal effects dynamically and identifies employment and earnings as primary drivers rather than treating “migrant” as one fiscal type. Real estimates require observed age, earnings, mortality, eligibility, service use and uncertainty. Civic Ledger's numbers are fictional and its index is illustrative; it can establish consequences of assumptions, never prove that the assumptions are true.