RE: Visa extension to 90/120 days...

So you are not actually avoiding an overstay fee. You are jumping through administrative hoops to pay the fee in advance! That's all!

Medical letter must be done here as you cannot request an extension prior to arrival.  Proof of solvency: a bank statement showing $$, receipt of rent paid or hotel payments, credit card limits and cc statements. Things like that as well as an airline ticket!

The "extension" is the same price as the overstay fee/fine, plus the medical fee, plus the hassle of collecting and submitting all the paperwork.  Friends have done it several times, and the last time, they didn't get the certificate/receipt until a few days after they returned home from the DR. They had a struggle at departure with not paying the overstay again,

@UncleBuck

Hola , I was wondering where your friends applied for the extensions for the overstay which government office  ( dept ) and how much time in advance before  the 30 day visa expiring  …. TY  .

@Tippj It all starts at Migracion's website.  Scroll down a bit, and the info is there.

https://migracion.gob.do/en/servicio/stay-extension/

@Tippj

https://migracion.gob.do/en/servicio/stay-extension/