VISA
For the vast majority of tourists, from most countries, a VISA ON ARRIVAL (or VOA) is all you need to enter Bali. This is a short stay (30-day) visa, available for purchase at the airport when you arrive or as an eVisa beforehand. The cost is R500,000 (A$50).
You can extend the 30-day visa for another 30 days. If you purchased the VOA at the airport, use a visa agent to sort this out for you. For the eVisa, you can extend it online. In both cases you will need to go to the immigration department (Immigrasi) in Denpasar to get stamped, so it's a bit of a palaver.
There are 10 Asian countries that don't have to pay. In these cases it can't be extended and you still have to GET the visa, but the fee is waived.
Here is a country-by-country list.
Here is the official e-Visa site to purchase your online VOA
There are other types of visas, including longer stay (6 months and above) so make sure you do your research on this. The VOA is single entry only, so you can't go to another country and then come back on this visa.
Note that these don't take long, but they sometimes get busy so give yourself at least 2 weeks before you travel. It's not more expensive at the airport but it's a pain.
ENTRY LEVY
A new entry levy was introduced in 2024, specifically for tourists. Again, you can pay this at the airport, but to beat the queue, purchase it beforehand online here. The cost is R150,000 (A$15, US$10).
Note that this is for Bali only. If you travel to another destination in Indonesia, you don't have to pay this. Also if you go somewhere else and then return, you have to pay it again so maybe try and work this into your travel arrangements.
CUSTOMS DECLARATION
You can now get your customs declaration online before you arrive in Bali. Another massive time saver, you can do this here up to 2 days before you leave.
In case you don't know bringing drugs of any kind is highly illegal. Don't do it. Even prescription CBB is illegal so be careful. You are also only allowed 1 litre of alcohol. My advice is to bring a bottle of white wine if you're staying in a villa...it's expensive here.
OTHER THINGS TO DO BEFORE LEAVING HOME
Download Whatsapp: this app is universally used by Indonesians. It's cheaper in Bali for locals to have wifi on their phones, and use public wifi, than to purchase packages that include SMS. This means they can rarely text or even call. We recommend downloading Whatsapp before you arrive if you don't have it already. Your drivers, hotels and restaurants all confirm through the app.
Download GoJek and/or Grab: These are the Indonesian Uber equivalent. It's cheap, convenient and you can get cars, motorbike transport, food deliveries and even deliver packages quickly and cheaply. Note that Gojek/Grab pickups are not allowed on the streets in central Ubud. You'll need to get a local driver for in-town trips as there are no bluebird taxis prowling the streets.
Bring Cash: Change ~A$50 equivalent at the airport and bring the rest in cash. You can exchange more cheaply than your bank will and cash is still king in Indonesia, so it's useful to have. Most hotels and restaurants will accept credit card, and you can get cash from an ATM, but if you're on a budget, this is the way to go. Please check your cash in front of the exchange guy before you accept it. The are a few bad apples.
Check my list of what else to bring with you in the article linked below.