I know this problem well

. In the past, the matrix of VAT rates has been changed many times. That is why I am prepared for such situations - I can define any number of VAT rates, with a maximum of seven rates being active at the moment. Why seven? Because only so many rates can be programmed in fiscal cash registers and it seems to me impossible for governments to introduce fiscal regulations that would suddenly require the exchange of millions of cash registers.
Most often, introducing changes to the matrices of VAT rates causes considerable problems when using fiscal devices. While, in the case Jimmy describes, it seems to be a simple reprogramming of rate groups, you have to do it one night on all devices in the country. But here you can also use software that will do it automatically. Worse, if you have to do it only for some products (what awaits me in the near future) and it is impossible to accurately determine by any algorithm which products should be converted to the new VAT matrix. You have to do it manually in hundreds of cash registers for thousands of products in one evening.
In addition, there are issues related to the return of previously purchased products. Cash registers, which have admission in my country, do not allow refund operations in "non-existent" VAT. You have to do it bypassing the cash register, if the store does not have the appropriate software, it must count manually.