Every government, however powerful, faces the same arithmetic. Money comes in through taxes and other revenue. Money goes out on public services, defence, investment and interest on past borrowing. The difference is either a surplus, which can pay down debt or build reserves, or a deficit, which must be borrowed. Understanding this arithmetic is the first step to understanding why governments make the choices they do, and it is the backbone of every turn in Geopolitics.

The four big levers

Most budgets can be described with a few numbers, each expressed as a share of the economy, or GDP:

  • tax revenue, the share of national income the state collects;
  • public spending on services such as health, education, pensions and administration;
  • defence spending;
  • public investment in infrastructure, research and long-term projects.

On top of these sits interest on the public debt, which is not a choice in the short run but a consequence of past decisions. Expressing everything as a share of GDP makes it easier to compare countries of very different sizes and to see whether the state is growing faster or slower than the economy that pays for it.

Deficits, debt and the ratio that matters

A deficit in one year adds to the stock of public debt. What matters for sustainability is usually not the debt in dollars or euros, but the debt compared with the size of the economy. A debt that stays constant while the economy grows becomes lighter over time.

Economists often summarise this with a simple relationship. If the interest rate the government pays on its debt is higher than the growth rate of the economy, the debt ratio tends to rise unless the government runs a surplus before interest, called a primary surplus. If growth is higher than the interest rate, the state can run small primary deficits and still see its debt ratio fall. That is why the same level of debt can be manageable for one country and dangerous for another.

There is no universal safe limit. When European Union members signed the Maastricht Treaty in 1992 they adopted reference values of 3 percent of GDP for the deficit and 60 percent for public debt. These are political rules rather than laws of nature, and many countries have exceeded them for long periods, but they show how governments try to anchor expectations.

Why bond markets matter

Governments borrow by selling bonds to investors. The interest rate investors demand depends on how confident they are that they will be repaid in full and on time. A state with a long record of stable institutions and moderate debt can borrow cheaply. A state that borrows quickly, or whose debt is already far above what investors consider comfortable, pays more, and higher interest makes the debt grow faster still.

Borrowing is not good or bad in itself. Debt that finances a road, a power plant or a better-trained workforce can raise future growth and pay for itself. Debt that finances everyday spending simply moves the bill to the future. The question a good finance minister asks is always: what will this money build?

Taxes and the mood of the country

Raising taxes is the most direct way to increase revenue, but it has side effects. Higher taxes leave households with less money and can slow economic activity. Sudden large increases also provoke resistance; history is full of tax revolts, from medieval uprisings to modern street protests. Most citizens accept gradual change more readily than a shock.

Cutting spending has its own costs. Public services are visible, and people notice when hospitals, schools or pensions get worse. A budget is therefore never only an accounting exercise. It is a statement about who pays and who benefits, and voters judge it.

Investment: the long game

Public investment is often the first item cut in a crisis, because its benefits are slow and its absence is not immediately felt. Over many years, however, underinvestment shows up as crumbling infrastructure and weaker growth. Governments that protect investment during difficult periods tend to have more room for manoeuvre later.

How the budget works in Geopolitics

In Geopolitics every campaign starts from real data for your country, including tax revenue, spending on services, defence and investment, public debt and the average interest rate. The budget window lets you set four levers: taxes between 10 and 50 percent of GDP, public services, defence and investment, with total spending capped at 60 percent of GDP. Before you confirm, the forecast shows your daily income and costs, interest, project upkeep and the expected growth rate. The preview uses the same formulas as the server, so what you see is what will happen.

The mood of your country reacts to your choices. Spending on services above your country's starting norm improves welfare, while taxes above that norm reduce it. A sharp tax rise also hits stability, and the effect grows with the square of the increase: a few points cause grumbling, a large jump brings people onto the streets. Investment above a modest baseline raises growth, while very high taxes slow it.

You can also manage public debt directly. Issuing bonds brings money into the treasury now, but markets absorb only a limited amount each month. The more you sell in a short time, and the further your debt rises above the level investors tolerate for your country, the higher the interest rate on new bonds and the more market confidence suffers. Repaying debt from the treasury lowers your interest bill for good.

Mood matters because elections come. Once about five months of game time have passed since the last vote, your country can go to the polls, and your odds depend on public approval, a combination of stability and welfare. You can campaign on generous promises, which cost money but improve your chances, run on your record or campaign for reform. Losing brings a hostile parliament that obstructs your government for 60 days.

Finally, the development league compares your country's economy, welfare, finances and development with a passive reference of the same country that keeps its starting policies. The finances score uses net debt, debt minus the money in your treasury, so borrowing simply to hold cash does not improve your result.

Practical tips

  • Change one lever at a time and watch the forecast.
  • Raise taxes gradually rather than in one jump.
  • Borrow for investment, not for everyday spending.
  • Keep a reserve for crises and fuel price shocks.
  • Watch stability and welfare when an election approaches.

For your first days in office, read the strategy guide to your first ten turns. To see how outside shocks hit your budget, read energy security and fuel markets explained. Then open the budget window and find out what kind of finance minister you are.