Yes, if you have paid the course fee you can download a signed letter of acceptance from your Utrecht Summer School account.
We only provide a letter of acceptance after the course fee has been paid completely and has been registered. As soon as the payment is registered you will receive a confirmation of payment via e-mail. From that moment onward you can download the letter of acceptance from your account.
The letter of acceptance can be useful (or even necessary) for your visa application procedure. You can find here whether your nationality requires a visa.