
CLSI accepts online payment using any major credit card.
Instructions for paying an INVOICE:
- Enter your invoice number(s) in the Reference Number field below. If you are attempting to pay multiple invoices, please enter each invoice number separated by a common.
- Click “Pay Now”. (You will be redirected to our third-party secure website for the transaction.)
Instructions for paying a RETAINER:
- Enter your project or proposal ID in the Reference Number field below.
- Click “Pay Now”. (You will be redirected to our third-party secure website for the transaction.)