What are the necessary steps and considerations when switching from a Non-B visa to a DTV visa in Thailand?

DTV approved in Hanoi 4 working days, freelance. Thanks for all the good advices, now is my time to return the favour and share my experience :

My first advice is for people like me switching from non-b visa to DTV : Cancel your visa or extension of stay and work permit prior to applying ! In my case this was my mistake, I exited Thailand while on extension of stay using a re-entry permit thinking that it was the safe way in case my application would be rejected.

However from my understanding this could be a good reason for the application being rejected, plus when coming back I was held at BKK immigration, the officer was very confused and did not know what to do, I told her that I wanted my non-B to be canceled and use DTV instead, she called 3 others immigrations agents for advice, in addition to long talkings on the phone, before finally stamping me with DTV. No questions were asked, and they were very friendly, they simply seemed confused about the right thing to do considering I had 2 valid visa and a work permit ...

Now I am back in Thailand trying to cancel my work permit, hoping will not have further problems with my local immigration ..

Second advice : have your DTV also ready in your phone, for my case I printed it on a strong paper in A5 format, but it was too big for their machines to scan the QR code and the officer looked quite annoyed 😅

Regarding documents, I provided :

1) Personal IDs documents :

- 1 copy of my first passeport page

- 1 ID picture from a photobooth

2) Return informations :

- Indicated that I was planning to leave 1 week after arriving

- Wrote the flight number of intended flight (did not actually made the booking for that flight)

3) Proof of sufficient funds :

-Introduction letter and a summary of all the balance sheets documents provided for each months so they can have a global view of all the documents

- Provided 9 months of bank statements showing over 500K bahts in my french bank from 2 different bank accounts (current + savings). For each statement I provided original + self translation copy, and highlighted on the translation copy the relevant informations (total balance, account number)

4) Employment Status :

- Introduction letter explaining my situation (freelance with a single client from France, yearly income)

- Service Agreement Contract (in Engligh) signed by my client and myself, explaining the current deal and income provided by my client

- Letter written by my client (in English), explaining that I worked for them for over 10 years, and that I was free to cary out my assignments in Thailand.

- Invoices from year 2025 with matching bank statements (again provided original + self translation with highlighted relevant informations)

- Portfolio examples, screenshots from my client's website showcasing products that I had developed for them being sold.

5) Location :

- Copy of passeport page showing Vietnam visa stamp

- Flight booking to Vietnam

- Copy of boarding pass from Bangkok to Hanoi

- Condo booking confirmation for 4 nights in Hanoi

Good luck everyone :)