Can I list courses I have signed up for but not completed?

Declaring it is allowed and often required. Dermatology's application has a Study in Progress section for courses under way, requiring a transcript or evidence of enrolment, plus a separate section where incomplete qualifications must be declared with reasons — and things completed but not yet formally awarded go in that section, not under qualifications ¹. So the honest answer is not "leave it off", it is "put it in the right box".

Whether it scores is a different question, and mostly it does not. RANZCO scores an incomplete PhD or masters at zero ². Orthopaedics requires a doctorate to be complete by a stated date in the selection year ³. Dermatology will not consider a publication awaiting acceptance, and an acceptance that arrives after the closing date does not count; presentations accepted but not yet delivered are excluded too ¹. The exceptions are worth knowing: urology scores a part-finished doctorate — 4 points for a pre-submission thesis review, 2 for confirmation of candidature ⁴ — and vascular gives 1 point for twelve months full-time towards a higher degree ⁵.

Label it precisely. The convention on the sub is to list the item with "pending" and the booked date so it reads as locked in rather than aspirational ⁶. For papers, "in press" once accepted, and "submitted" only if you are comfortable being asked about it ⁷.

Do not round up. Dermatology's policy treats misleading information as grounds for refusing an offer regardless of rank, and says it may result in a lifelong ban on future applications ¹. A course you attend in November is worth less than the fifteen seconds it takes a panel to notice you called it complete in July.