Any chance you have a Matrix account? That might be better suited for chat.

Anyway:

• you have to be a registered VAT payer (plátce DPH in Czech, not sure of the official English term) to buy stuff without VAT. That can happen one of two ways:
  • mandatory VAT payer - when you reach 1 million CZK in revenue for the last 12 months
  • voluntary VAT payer - you can register yourself voluntarily as a VAT payer. From what I've heard, they want some kind of proof that you actually need to do that, like a contract or invoices with another VAT payer

The VAT deduction works only from other VAT payers, so it really depends what you want to do.

• If you sell to non-VAT payers which also includes all end-users (spotřebitel), you have to add your own VAT, so you gain nothing - if you buy something for 121 CZK, you effectively pay 100 CZK without VAT, if you then sell it to an end-user without profit, you have to add VAT, which means you sell it for 121. You then have to pay the 21 CZK VAT from your sale (more specifically you don't pay any VAT because you subtract VAT you paid from VAT you should pay, which in this case is 21-21=0)
• if you sell between two businesses, both of which are VAT registered, you deduct the VAT the same way. Generally you don't care about VAT in such transactions, because the real cost is the price without VAT and the rest is just accounting bullshit. You buy from VAT payer for 100 without VAT, which means you pay 121, then you sell to another VAT payer for 121 (including VAT) and your VAT is again 0 (21 should pay - 21 paid)
• you are a VAT payer and buy from non-VAT payer, sell to anyone. This is the worst case. You buy from non-VAT payer, meaning you can't subtract any VAT, but you have to add your VAT when selling. This situation sucks.
  • to VAT payer - you buy for 100, no VAT deduction because seller is not VAT payer, you sell to a business for 121, you have to pay 21 CZK VAT, effective price for them is 100 CZK (they can deduct your VAT)
  • to non-VAT payer, you buy for 100, sell for 121, meaning you have to pay 21 VAT and the effective price for them is 121, meaning you're more expensive and have gained nothing
• and last, the only scenario where you actually gain something - you buy something from a VAT payer and don't sell it further, for example a laptop to work on. You deduct the VAT, but don't add any because you didn't sell it. Note that because of this you can only buy stuff that you need for your business (and you wouldn't buy something unrelated to steal from the country, right? wink, wink). Note that you should always be ready to explain to the government why you bought what you bought and why you need it for your business. It hasn't happened to me yet in the 11 years I'm self-employed but it can happen. My cousin had like 3 of these government checks in the same time because he likes to deduct VAT on his new cars.

Note that the last point is why they want some proof that you actually need to be registered for VAT, otherwise everyone would just become a VAT payer and buy stuff without VAT even though they don't need it.

As for how often, when you register for VAT, you need to pay monthly, you have until 25th each month to send "kontrolní hlášení" (control report or something like that) where you declare each transaction and afterwards pay the difference between VAT for stuff you sold and stuff you bought.

You will pay to a bank account for VAT for the region you're registered in.

As for how to fill the form, I don't know, when I became VAT payer, I found an accountant to do all that stuff.