The local currency is Hungarian Forint.
Legislation on the controls of cash entering or leaving the EU applies in all Member States. Any person entering or leaving the EU will have to declare the cash that they are carrying if this amounts to 10,000 Euros (or equivalent) or more; this includes cheques, travellers’ cheques, money orders, etc. This will not apply to anyone travelling via the EU to a non-EU country, as long as the original journey started outside of the EU and will not apply to those travelling within the EU.
Don’t use street money changers. Take care not to accept bank notes that are no longer valid but which are still in circulation. There have been a small number of reports of taxi drivers deliberately passing these notes to tourists - as well as notes from neighbouring countries that are not valid in Hungary.