I have a Thailand Pass and enough healthcare cover for three months

 

I also have a 30 Day Visa

 

is it necessary to renew my visa after 30 days to avoid extra charges 

 

Thank you in advance

I’ll move your question to the appropriate forum where someone will, I’m sure, advise.

 

This forum is for those seeking advice for travelers from Thailand. 

I’m not sure what your question is asking. 

 

The Thailand Pass is unrelated to your visa and is simply permission to enter and proof that you have met the requirements (vaccination) and Test&Go (quarantine) booking)

 

IF you enter on a 30 day Visa (or 30 day Visa exempt stamp) and wish to stay longer you will have to find a way to extend your stay. 

 

Thank you much appreciated 

From your post, it appears you plan to enter without a Visa (Visa Exempt) and will receive a permission to stay of 30 days.  Before the period ends, you can go to a Thai Immigration office and extend your stay one time for another 30 days - fee is 1.900 baht. 

 

If you remain in Thailand after your permission to stay expires, you will be in Thailand illegally. If caught before departing, you would be placed in detention and then deported at your expense.  If not caught, when you depart Thailand, Immigration will charge you a fine of 500 baht for each day of overstay up to a maximum fine as I recall of 20,000 baht.

16 hours ago, Lotusflower6 said:

I have a Thailand Pass and enough healthcare cover for three months

 

I also have a 30 Day Visa

 

is it necessary to renew my visa after 30 days to avoid extra charges 

There are no 30 day visas, if you come to Thailand without a visa you will get a visa exempt entry for 30 days that can be extended for a further 30 days.

if you have a tourist visa you will be stamped in for 60 days and can extend for 30 days.

 

as above it is a bad, and sometimes only expensive, idea to overstay,

 

An extension for ฿1,900 is almost always cheaper, it is always safer.

As stated, there is no 30-day visa (except in the unlikely event that you have a transit visa, in which case you cannot extend). Assuming entry without a visa, receiving a 30-day visa exemption, you can extend one time for a further 30 days. Then you have some options for legally staying longer, but they are not easy. It will usually be better to leave Thailand and return if you want to extend your stay.