The Cortes
The people, fed up with the kings' demands, sometimes rebel in tumultuous ways. Faced with a wave of popular uprisings, kings sometimes gave in and agreed to consult their subjects when imposing taxes and deciding how to apply them. Taxes begin to be paid to cover certain public expenses. And the taxpayer will become the main protagonist of the resistance against the king.
Typical examples of these limitations on royal power were given in the Cortes held in León (1188) and in the Magna Carta of England (1215), which proclaimed the principle that taxes must be consented to by the person who has to pay them.
One day an emperor educated abroad arrives in Spain. Their imperial policy requires enormous expenditures and subsidies. The Cortes of Castile and León, composed of representatives elected by the cities, are reluctant to accept new exactions. The fifteen main Castilian cities rise up in rebellion in the Junta of Ávila. One of their complaints: “The intolerable impositions and burdens that these kingdoms have suffered.”
The royal army would suppress the comunero movement. But the monarchs' struggle with the Cortes did not always favor the former, who often had to submit to the conditions agreed upon by the Cortes if they wanted to obtain the sums they needed.
The remote origin of the Public Budget lies in agreements of this type between the rulers and the Cortes, as a document approved by Parliament and by which the Government is authorized to collect certain income and make certain expenses throughout the year. The history of popular sovereignty owes much to the history of the Budget.
With this control by Parliament, the Treasury is less at risk of being used by kings and rulers at their whim, and a certain order is introduced into the raising of revenue and the making of expenditures.
And once the king becomes accustomed to seeing his power limited by the Cortes' decisions on tax matters, the independent legislative power of the monarch himself is born, which is entrusted to popular representation.