There are no rules stating that a cover letter should be included in a visa application; it's an entirely optional step and in the vast majority of cases a cover letter is not provided.
Also, there are no guidelines for what a cover letter should say or what its purpose is. Accordingly, this answer provides ideas and suggestions only.
Header and subject
Your own name, address, mobile number, email address, and application date.
The appropriate consulate should be identified...
Consulate General of France in St Petersburg
12, avenue Nevsky, 5th floor
191186 St. Petersburg
The subject of the letter should identify the applicant...
Subject: John Marley Jones, Canadian national, DOB 4 April 1990
There is no need for a salutation if you don't know the visa officer, and under the subject is the attachment list...
Attachments (for a Schengen) should be listed in descending order of priority
- Canadian passport #112234545 expiry 13 April 2025
- Invitation from World Finance Inc, dated 1 June 2017
- Itinerary, 5 August 2017 to 20 August 2017
- Flight booking, British Air, 5 August 2017 and 20 August 2017
- Accommodation booking, Marriott Rive Gauche, dated 13 June 2017
- Six (6) Bank statements, HSBC, covering 1 Jan 2017 - 1 July 2017
- Employment contract, Bristol Chemistry, dated 5 June 2014
- Tenancy contract, marriage license, etc etc (more attachments go here)
This is best presented as a table...
Name/Nationality Relationship Address Telephone
Mary Jones Aunt 123 Green Street 07739 49959
French Paris 33445
Thomas Smith Friend 83 Red Street 9399497 945
(Algerian) Paris 394958
Body of the letter
This is optional text which summarises the application and provides any additional explanations in support of the application. A well composed cover letter can have an immeasurably beneficial effect for an applicant, but providing text is not without risk. Consider these points...
- A cover letter can introduce contradictions and ambiguities that can
have an adverse effect on the outcome.
- Long-winded and pointless digressions may be deemed as incoherent and
have an adverse effect on the outcome.
- Meaningless attestations can be interpreted as the applicant does not
understand the visa process and hence elevate the risk.
- Similarly, effusively maudlin apologies and excuses can backfire by highlighting lack of planning, lack of foresight, lack of understanding the rules.
I like to devote a paragraph to the premise and any grounding occasions for the application and may devote another paragraph to highlight any special change in circumstances that have occurred between the current and previous applications. If the applicant does not have an adverse history, the second paragraph can highlight the performance history. If there is no performance history, I will devote the paragraph to professional positions occupied by the applicant's close family (police, magistrate, teacher, medical practitioner, and so on).
If the text goes on for more than two or three paragraphs, or takes more than a half-page, something may be wrong with your understanding of what's needed and a professional should be consulted.
As far as style goes, spelling, punctuation, and composition can have a favourable effect or can further contribute to a conclusion that the letter is incoherent.
Sometimes I have faxed a 'transmittal letter' to the national agency, this is a different communication and not to be confused with an application cover letter.
Finally, note that visa applications are submitted to a third-party contractor, either a VFS or VAC. It has been widely and credibly reported that VFS personnel in South Asia are removing evidence from an applicant's bundle to the detriment of the applicant (hence the enumeration of evidence in the cover letter). Of course you should take steps to avoid this possibility, but if you think evidence has been removed, you can post your cover letter only directly to the consulate with an explanation of why you think your evidence has been tampered with.
Your question is...
But what about those who apply for their very first Schengen visa, and
therefore have to do it in person? Is cover letter really needed or
As explained, the whole concept of cover letters is an option that may or may not benefit the applicant. But consider that a first application is no different than any other application and your interviewer may not be the decision-maker. If nothing else, a cover letter can help you organise and present your answers in a way that shows preparation and a professional approach.
We cannot approve your cover letter here at TSE and please do not ask us to do so. Cover letters contain highly personal information which makes them meaningless when they are redacted. Also, questions about whether or not a given cover letter passes muster are seeking an opinion poll (which are off-topic here).