Applying for a BNPL agreement usually only involves a soft credit check, so this shouldn’t affect your credit rating if you keep up with payments.
However, some providers including ClearPay and LayBuy will do a hard credit check before you set up an account with them.
Klarna started reporting all purchases to credit references agencies using its Pay in 30 days and Pay in 3 BNPL schemes made on after 01 June 2022. This includes all purchases that are paid on time, as well as late or missed payments. It has said it won't report any attempts to make a Klarna purchase that are rejected.
If you miss any payments, your BNPL provider (including LayBuy and OpenPay) can report this to the credit reference agencies and this would affect your credit score.
Even if your BNPL purchases don’t appear on your credit score, if you are applying for other credit you may be asked about any BNPL products you’ve got when your provider does their affordability assessment and if you have made a lot of use of BNPL products this might affect your access to other forms of credit.