From today, applicants can now pay and send their completed applications to UCAS. Unis and colleges can also start making decisions on applications that they've received.
You don't have to rush to submit it, however! To ensure you get equal consideration for your application, you have until 15 January to submit your application for most courses, unless you're applying for Oxford or Cambridge, or most courses in medicine, vetinary medicine/ sciences, and dentistry, the deadline for which is 15 October.
Click here for an overview of the undergraduate application process.