When you upgrade to a premium account on ProtonMail you can choose which currency you want to use for payment. The current available currencies are the euro (EUR), the United States dollar (USD) and the Swiss franc (CHF).
To change the currency when upgrading to a premium account, go to Settings > Dashboard. Then select the currency you wish to use from the dropdown menu in the top right of the screen.
Once you have selected the currency you want to use, proceed with the upgrade by clicking Select plan on the plan you wish to use. All subsequent payments will be made in that currency, unless you change it again.
Changing the currency for an existing Plus plan
If you have already upgraded to a Plus plan, you can change the currency you use for future purchases. ProtonMail accepts payments in USD, EUR, or CHF.
To change the currency, go to Settings > Dashboard and then select Customize subscription.
Select the plan you are on (or select a different one if you would also like to change your plan) and select your preferred currency from the dropdown menu in the top right corner.
Note: Changing the currency also extends the duration of your premium plan, which means you will be charged again, but not the full amount. Depending on how long the plan has been used, you will be only charged the difference for the extension.
For example, if you pay monthly on the 10th of August, the Plus plan will last until the 10th of September. If you then decide to change the currency on the 20th of August, the plan will be extended until the 20th of September and you will only be charged for the 10-day difference, not the full amount for one month.