Peru is not a cash-only country any more, but it is not a card country either. It sits in between, and the trips that go badly are the ones where somebody assumed one or the other.

Here is what actually matters, in the order you will run into it.

The currency

The currency is the sol, written S/ and sometimes called nuevo sol out of habit. Notes run from 10 to 200 soles; coins from 10 céntimos to 5 soles.

Dollars are accepted in some hotels and agencies, but at a bad rate and only if the note is pristine. A dollar bill with a small tear is routinely refused. Do not plan around dollars.

Change money at a casa de cambio in the city centre rather than at the airport, where the rate is noticeably worse. In Cusco the exchange houses around Avenida El Sol are the usual choice.

The 200-sol problem

This is the single most useful thing to know: nobody wants to break a 200-sol note, and often not a 100 either.

Taxis, markets, small restaurants and rural shops simply will not have change. You will be sent away to find it yourself.

Break big notes whenever you get the chance: in supermarkets, at your hotel, in a pharmacy. Keep a working stock of 10s and 20s and treat them as the useful money.

ATMs

ATMs are everywhere in Cusco, Lima and Arequipa, and scarce or absent once you leave the towns. Withdraw before heading to the Sacred Valley or a trek.

Most Peruvian banks charge their own fee on top of your bank's. It varies, so it is worth trying two different banks on your first withdrawal and comparing the deducted amount.

Machines will offer to do the currency conversion for you. Always decline and let your own bank convert: accepting is a guaranteed worse rate.

Withdraw larger amounts less often. Each withdrawal carries a fixed fee, so four small ones cost far more than one big one.

Use ATMs inside a bank branch or a supermarket rather than one on the street, and prefer daytime.

Where cards work and where they do not

Cards work in hotels, established restaurants, supermarkets, agencies and the bigger shops. Visa is accepted more widely than Mastercard; American Express rarely.

Cards do not work in markets, on public transport, in taxis, at most trailheads, in village shops or for tips. That is a lot of the trip.

Tell your bank you are travelling before you go. A card frozen for suspicious activity on your second day is a common and avoidable problem.

How much cash to carry

For a normal day in Cusco, 100 to 150 soles covers food, taxis and entry fees comfortably.

For a multi-day trek, carry what you need for tips plus a margin: there is nowhere to withdraw, and tipping the crew is expected and done in cash.

Split your money. Some on you, some in the hotel safe, and a spare card kept separately from the first.

Tipping, briefly

Tipping is not obligatory but it is customary in tourism. In restaurants, around 10 % if service is not already included.

On treks, the guide, cook and porters are tipped at the end, in soles, and it is the single reason most people need more cash than they planned. Ask your operator for the usual range before you leave Cusco.

Small things that save trouble

Keep coins for public toilets, which charge one sol almost everywhere.

Count your change. Not because anyone is cheating you, but because small notes get mixed up easily.

Refuse torn or heavily taped soles when you receive them, because you will have the same trouble passing them on.