U.S. Tesla customers can now use Bitcoin for future purchases, according to Ars Technica. While it’s only available in the U.S. for now, Tesla CEO Elon Musk said he plans to expand the option worldwide later this year.

“You can now buy a Tesla with Bitcoin… Tesla is using only internal & open source software & operates Bitcoin nodes directly,” Musk announced today on Twitter. “Bitcoin paid to Tesla will be retained as Bitcoin, not converted to fiat currency.”

Tesla has spelled out the process of buying a new vehicle with Bitcoin in its new “Bitcoin Terms & Conditions” policy, according to Yahoo Finance. All the vehicles will still be priced in U.S. dollars, so customers will pay the equivalent price in Bitcoin.

However, according to the rules, if the transfer is not begun during the Bitcoin Price Window, the Bitcoin price will then expire. A new Bitcoin price will be generated per customer request.

While Bitcoin prices vary, customers who use it to pay for their vehicles have the advantage of lower taxes. Tesla recently purchased $1.5 billion in Bitcoin.

Customers can opt to continue to buy Tesla cars in U.S. dollars if they are convinced the price of Bitcoin will continue to soar. It is also up to the discretion of Tesla whether they refund any bitcoin payments in USD or Bitcoin, which could possibly be a disadvantage for customers.