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1. Surplus/deficit vs. changes in debt
2. Population
3. Calculations
4. General remarks on the interpretation of the data
5. Currencies and exchange rates
6. Updates
7. Terminology

1. Surplus/deficit vs. changes in debt

It is important to note that the Maastricht surplus/deficit on the one hand and variations in the Maastricht debt on the other hand are not defined identically. There are, for example, transactions that change a Member State's debt level without changing the Member State's budget surplus/deficit. The difference between both figures (surplus/deficit vs. changes in debt) can be of substantial size.

The table below provides the structure (including example data for 2012) which explains the contributions of the deficit/surplus and the other relevant factors to the variation in the debt level. The original EDP Notification Table for the general government sector (table 3A) of France from October 2013 serves as an example.
Maastricht surplus/deficit vs. changes in Maastricht debt (example: France 2012)
Source: Eurostat, EDP Notification Table of France, October 2013, page 7

2. Population also reports a Member State's population data on 1 January of the respective year. Reported data are obtained from Eurostat's statistic "Population on 1 January (tps00001)" and are not updated every second (constant values). Population data are simultaneously updated with debt, deficit/surplus and GDP data (usually in April and October). If no new population data are available at the time of update, will temporarily continue using the previous year's data.

3. Calculations

The following calculation formulas show how the debt, surplus/deficit and GDP clocks are computed on As an example, it shows the formulas for 2018 (previous year) and 2019 (current (planning) year). The current year is the year of the last update. Data from the previous year can represent half-finalised, estimated or final data (in most cases: half-finalised). Data from the current year are always planning data (forecasts).

Gross domestic product (GDP):

change (+/−) per second
=  (GDP 2019  −  GDP 2018)  /  number of seconds per year

absolute nominal GDP p.a.
GDP 2018  +  change per second  ×  number of seconds since 2019-01-01 00:00

change in nominal GDP (+/−) p.a.
=  (GDP 2019  −  GDP 2018)  ×  100  /  GDP 2018

nominal GDP per citizen
=  absolute nominal GDP p.a.  /  population on 2018-01-01

Public debt:

change (+/−) per second
=  (public debt as of 2019-12-31  −  public debt as of 2018-12-31)  /  number of seconds per year

absolute amount of public debt
=  public debt as of 2018-12-31  +  change per second  ×  number of seconds since 2019-01-01 00:00

public debt per citizen
=  absolute amount of public debt  /  population on 2018-01-01

public debt to GDP ratio
=  absolute amount of public debt  ×  100  /  absolute nominal GDP p.a.

Surplus/deficit (+/−):

change (+/−) per second
=  (surplus/deficit 2019  −  surplus/deficit 2018)  /  number of seconds per year

absolute surplus/deficit p.a.
=  surplus/deficit 2018  +  change per second  ×  number of seconds since 2019-01-01 00:00

surplus/deficit per citizen
=  absolute surplus/deficit p.a.  /  population on 2018-01-01

surplus/deficit to GDP ratio
=  absolute surplus/deficit p.a.  ×  100  /  absolute nominal GDP p.a.

4. General remarks on the interpretation of the data

At first glance, debt clocks (the same analogously applies for deficit/surplus clocks and GDP clocks) suggest that they show the exact amount of public debt in the very moment one looks at it. It is, however, important to note that debt clocks actually cannot provide this kind of accuracy:

Firstly, because debt clocks assume a country's debt to change continuously at a constant rate (linear trend). Yet, no country's public debt changes that way. Instead, the amount of national debt fluctuates and may, for example, soar at some point of time during the year. At another point of time it decreases (despite a trend to increase), for example, because the government just realised tax revenues. A country's debt may also stay constant for some time (for example, over Christmas when hardly any employee of the debt management departments works).

Secondly, since debt clocks are usually based on half-finalised data (previous year) and planning data (current year). Especially planning data imply a susceptibility to errors.

Thirdly, because a country is usually not comprised of one public entity but possibly rather up to thousands of public entities that contribute their part to the increase/decrease of an entire country's public debt. Germany, for example, has one federal government, five kinds of social security funds (including, for example, more that 140 health insurance funds), 16 state governments and more that 10 000 local governments (plus several thousand state-owned companies being classified with the public sector). This leads to situation where, in the true sense of the word, 'nobody' knows the exact amout of debt at this very moment. Statistical offices rather collect the public entities' debt reports after the end of the year. Based on these reports they compute the level of debt as of 31 December.

Debt clocks, therefore, rather reflect a rough estimate of the current amount of debt. However, they still fulfill an important function: They visualise the approximate trend and average change in public debt in a simple and even for non-professionals understandable way.

5. Currencies and exchange rates

Debt, deficit/surplus and GDP data are shown in the EU Member State's respective currency. In order to improve comparability of Member States with different currencies, the section "general information" includes a link to the European Central Bank's (ECB) website showing current exchange reference rates.

6. Updates

The three types of clocks on (public debt clocks, budget deficit/surplus clocks and GDP clocks) are based on EDP Notification Tables published by Eurostat in April and October of the respective year. Eurostat's tables include in both cases data for the previous year and data for the current year. That means, for example, that the tables of April and October 2019 report data for 2018 (usually half-finalised) and 2019 (planned) − but not for 2020. Data concerning 2020 are published not before April 2020. This implies that at the beginning of every year (until April) is forced to use the previous year's October data − until it is possible to update the calculation formulas in April. This limitation is to be to kept in mind when interpreting the clocks at the beginning of a new year.

The author of aims to update the website's calculation formulas as promtly as possible., however, is an online project that is operated volutarily in the author's leisure time. Therefore, some time lags between Eurostat's publication and this website's update cannot be ruled out entirely.

7. Terminology

The analysis of a country's financial data requires the use of several rather technical terms, like e.g. "government consolidated gross debt" or "surplus/deficit to GDP ratio". To facilitate understanding, provides visitors with a small glossary on public finance terminology. To a large extent, this glossary is based on definitions published by Eurostat. - Public debt and budget deficits under the Maastricht Treaty

   Andreas Burth
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