I was at immigration office Phuket town all day giving information. Itâs indeed correct, visa with expired date 28-29 March can extend on Monday 30th March without penalty.
I was assisting immigration Phuket today for all day, you canât do any visa rum currently so you have only the option to apply for âCovid 19 extensionâ and here we advice everyone to do this only 1-2 upfront of your expiry date, so in your case April 16th. I would go 11-12th as they might close for Songkran...
once again to make it clear , if you leave Thailand and you would like to return (if you can) you need a medical certificate that youâre fit to fly and that you show no signs of C-19 infection + an insurance that covers up to 100.000$, including Covid-19.
The insurance that you mention can only be used when youâre living inside Thailand. Canât be used to enter the country again once you have left.