Whether you need a health form or not depends on what certificate of vaccination you have. If your certificate is not acceptable you still have to complete the form
All passengers arriving in Spain by air (except children under 12 years of age and those in international transit), regardless of the country of origin, including Spaniards returning to their home, must have one of these documents:
DIGITAL COVID CERTIFICATE OR EU EQUIVALENT vaccination against COVID-19 or a negative certificate of an active infection diagnostic test or a certificate of recovery after passing the disease. You can check if your certificate is valid on the website https://spth.gob.es or in the Spain Travel Health app -SpTH- (Android, iOS, Huawei).
Upon arrival at the airport follow the signals indicating the ORANGE WAY .
QR SPTH . If you do not have the EU Digital COVID Certificate or EU equivalent, you must fill in the SPTH Health Control Form manually entering the data of your vaccination, recovery or diagnostic test certificate through the website https://spth.gob.es or the Spain Travel Health application -SpTH- (Android, iOS, Huawei). The system will send you a QR code that you will have to present both prior boarding, and upon your arrival in Spain. In the health control, you may be required to present this document certifying vaccination, diagnostic test or recovery.
Upon arrival at the airport follow the signals indicating the BLUE WAY .
The UK certificates are acceptable. Below is the link to the page where you can upload your info to see if your certificate is acceptable or if you need to complete the form
https://spth.gob.es/spain-validator