Iran is still a cash economy, so bring enough hard currency for the duration of your stay. US Dollars and Euros are the most useful, and new and large (USD 100 or EUR 100 or higher) bills in good condition are preferred and usually get a better rate. Trade embargoes mean that banks will not forward cash advances on your foreign credit cards and they are only accepted by select stores for large purchases, such as Persian rugs. Most will be happy to forward you some cash on your credit card at the same time as your purchase. If you are desperate for cash, you can also try asking these shops to extend you the same favor without buying a rug or souvenir, but expect to pay dearly for the luxury.
Travelers’ Checks: Although in theory central banks in provincial capitals are able to cash them, the paperwork and time involved make them impractical for tourist use.
There is little point in risking the black market moneychangers who loiter outside of major banks and only offer marginally better rates than the banks. Central banks in most cities will change money for you, but the process can be a drawn out affair requiring signatures from countless officials and a fair deal of running around.
A better compromise is the private exchange offices (sarāfi) scattered around most large cities and major tourist centers. Although their rates are comparable to those of the banks, they are far quicker and, unlike their black market colleagues, they can be traced later on if something goes wrong.
The most widely-accepted currency is the US dollar, but Euros and UK Pound Sterling are also widely used. Other currencies are harder to change. $100 notes attract the highest prices, and you will be quoted lower rates for any old or ripped notes.
Bargain ruthlessly when buying handcrafts, rugs or big ticket items and modestly when hailing private taxis. In most other aspects of life prices are fixed. Tipping is usually accepted. Locals will generally round up the bill in taxis and add around 10% in classy restaurants. Porters and bellboys will expect $2 to $3.
If you are prepared to stay in the cheapest guesthouses, travel only by bus and eat only at fast food outlets or kebab houses, you can get by in Iran on a minimum of around $15 per day. If you want to eat a decent restaurant meal every now and then and stay in mid-range accommodations, a more realistic budget is around $40. If you want to eat and sleep in luxury and fly between major sights, you can easily chew through $100 per day.