1. Taxes
Mateusz Szczurek

2. What is a tax?
A levy imposed on an individual or legal entity by a state or local government to fund various public expenditures.
Payment of tax normally does not generate direct reciprocal commitment. There should be no reference to specific benefit received (as opposed to a user fee or toll).
In practice the definition is somewhat blurry: court, driving licence, passport, RTV fees are considered as non-tax revenues by OECD
Payments allowing selling alcohol or tobacco, hunting, fishing, gambling, permission to own a dog or a car are taxes.
Social security contribution are a border-line case - often included in the total tax burden (OECD)
Early taxes, eg. ancient Egyptian corvée (forced labour), or tithe were not monetary.

3. What are taxes for?
State's functions have to be financed. Taxes provide majority of revenues for the state.
Other sources of income: state owned companies' profits (typically natural resources)
Sale of state assets (short-term solution)
Debt, usually residual

4. Are taxes only for collecting money for the state?
Functions of taxes
Fiscal: providing financing for the state
Redistributive
Stimulating and discouraging via repricing
Correcting externalities and other market failures
Informative: about the state of the economy
VAT revenues as a proxy for GDP growth

5. Good taxes (Adam Smith’s Wealth of the Nations)
Vertical equity
The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state.
Horizontal equity
Certainty and similar treatment of similar cases
Efficiency of tax collection / ease of payment
Right level of taxation

6. OECD classification of taxes
Taxes on income, profits and capital gains
Individuals', Corporate
Social security contributions
Employees, Employers, Self-employed or non-employed
Taxes on payroll and workforce
Taxes on property
Recurrent taxes on immovable property (real estate)
Recurrent taxes on net wealth
Individual or corporate
Estate, inheritance and gift taxes
Taxes on financial and capital transactions
Other non-recurrent taxes on property (eg. one-off tax on net wealth)
Taxes on goods and services
Taxes on production, sale, transfer, leasing and delivery of goods and rendering of services
General
VAT
Sales taxes
On specific goods and services
Excise
Customs and import duties
On exports
On investment goods
Profits of fiscal monopolies
On use of goods or on permission to use goods or perform activities
Other taxes

8. Oecd

9. Tax on property (% of GDP), source: OECDUK FR BE

10. Taxes on goods and services (% of GDP)HU DK
GR, SLV

11. Literature
Smith, Adam, An Inquiry into the Nature and Causes of the Wealth of Nations., Book V, Chapter II Edwin Cannan, ed <
OECD, 2015, The OECD classification and interpretative guide, interpretative-guide.pdf