Refers to the way a payment is made, such as cash, credit card, bank transfer, or digital payment.
このお店では、いろいろな決済方法が使えます。
You can use various payment methods at this store.
オンラインでの決済方法を確認してください。
Please check the online payment methods.
You choose a payment method at the online shop.
I want to change my registered payment method.
I registered my credit card as a payment method.
More and more shops are using e-money as a payment method.
支払い方法 is the more general, everyday term for 'payment method', while 決済方法 is slightly more formal and typically used in business or online transaction contexts.
決済手段 emphasizes the 'means' by which payment is completed, whereas 決済方法 emphasizes the 'method' or procedure, but the two are used almost interchangeably in business settings.
Compound of 決済 (けっさい, 'settlement of accounts') and 方法 (ほうほう, 'method'). The exact historical derivation is straightforward; the word is a modern compound used in financial and commercial contexts.