In some edge cases (like mine) we have clients that can't use a credit card, but we still want to have all the data in Stripe. So we create a subscription with collection_method = 'send_invoice' and the manually sent the invoices to be paid, once we received payment we just change the status manually in Stripe.

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$model->invoice(['collection_method' => 'send_invoice']);
$subscription->invoice(['collection_method' => 'send_invoice']);
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When you use this collection method you can't apply $stripeInvoice->pay() function, you need to use the $stripeInvoice->sendInvoice();

When using the $stripeInvoice->pay() on when a colletion_method is 'send_invoice' it throws PaymentFailure, it doesn't require a payment method.

The only two options in 'collection_methods' is charge_automatically (default) or 'send_invoice' there fore using a simple if else statement.

https://stripe.com/docs/api/invoices/create#create_invoice-collection_method