UK Government guidelines state that the Union Flag should be flown on Remembrance Sunday (the second Sunday in November).
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
Scottish government guidance also lists Remembrance Sunday as a flag flying day.
The Union Flag is specified.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The Royal British Legion recommends flying the Union Flag on Remembrance Day (11 November) and Remembrance Sunday.
https://support.britishlegion.org.uk/app/answers/detail/a_id/263/~/remembrance-faqs
The flag should not be flown at half mast on either day.
The Birthday of HM The King is listed as a flag flying day by UK government guidance.
The Union Flag is specified.
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
The Birthday of HM The King is also listed as a flag flying day by Scottish government guidance.
The Scottish Saltire is specified.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The International Transgender Day of Remembrance honours those murdered as a result of transphobia.
It is an official flag flying day in Scotland but not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
St Andrew’s Day is Scotland’s national day.
St Andrew’s Day is listed as a flag flying day by Scottish government guidance.
The Scottish Saltire is specified.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
St Andrew’s Day is also listed as a flag flying day (for Scotland only) by UK government guidance.
The Union Flag is specified.
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
World AIDS Day takes place annually on 1 December. It is an international day first held in 1988 and dedicated to raising awareness of the AIDS pandemic and mourning those who have died of the disease.
World AIDS Day is an official flag flying day in Scotland but not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The birthday of the Duchess of Rothesay (Princess of Wales) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The birthday of the Duchess of Edinburgh (and Countess of Forfar) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The start of LGBT+ History Month is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The birthday of the Duke of Edinburgh (and Earl of Forfar) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
International Workers’ Memorial Day is a day of remembrance and action for workers killed, disabled, injured, or made unwell by their work.
It is an official flag flying day only in Scotland, not in the rest of the UK.
The saltire(s) should be hoisted right up and then lowered to half-mast for the day.
https://www.gov.scot/publications/flag-flying-on-government-buildings/