Changing the currency for your paid plan
If you have a paid Proton plan, you can choose which currency you want to use to pay: euros (EUR), US dollars (USD), or Swiss francs (CHF).
You can choose your currency when you upgrade to a paid plan.
How to choose the currency when upgrading from Proton Free
To change the currency when upgrading to a paid plan:
Log in to your Proton Account at account.proton.me on a computer and click Settings → All settings → Upgrade plan.
Then, select the preferred currency. You can now choose a plan you wish to upgrade to.

All subsequent payments will be made in that currency unless you change it again.
Changing the currency for an existing paid plan
You cannot subscribe to the same plan and duration, however, if you change the subscription to another plan, you can change the currency to one of our main currencies like EUR, USD and CHF. Depending on the region, you may also be able to choose your local currency if it’s supported.
Log in to your Proton Account at account.proton.me, go to Settings → All settings → Subscription and select Edit billing cycle.

Select your preferred currency in the Summary section at checkout.

Note: Changing the currency also extends the duration of your paid plan, which means you’ll 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 10 August, your paid plan will last until 10 September. If you then decide to change the currency on 20 August, your plan will be extended until 20 September, but you will only be charged for the 10-day difference, not the full amount for one month.