Cell data input auto adjusts to value relative to input

How do I proceed, with finding a formula or method, to auto adjust a value in one cell, based upon the input of another?
In this, I need to add VAT 20% when a UK sale, and export VAT (0.00%) - so in simple terms, If add cell value A1 as “UK”
it automatically applies “20 %” (as the tax rate) in cell B1.

I would use this formula with a drop down menu - (validity / cell range etc ) using 3 letter alpha codes for countries.

Thank you for any suggestions:

EXAMPLE.xlsx (5.8 KB)

Two possible approaches in the attached file:

  1. Hard code the 20% in a formula (products aaaa and bbbb). Simple formula but if the tax change, yu will have to update the formula on every row.
  2. Use the vertical lookup function VLOOKUP to search for the tax value (product cccc and dddd).
    EXAMPLE.xlsx (6.2 KB)

The data stretches to more than 25,000 in the period, I am working with, so I’d prefer it was automated.
EXAMPLE.xlsx (8.5 KB)
i tweaked the example here, to show how it will be used

While it is a significant number, copying a formula to 25,000 rows can be done in a few seconds. If you expect a magical solution without a column calculating the tax, or without a formula calculating the final price, then I am afraid that you will be disappointed.

I’m certainly not expecting to calculate anything, without a formula. I use large sheets to calculate a wide range of tax / sales / purchases etc.

I simply was looking for a method to type in a cell “A” which ensures the adjoining cell displays “B” - from that value - additional cells would calculate the rest of my formulas, and sort etc
ie.
UK in cell A1 ensures adjoining cell data in A2 displays 20.00 %.
Any other country in A1 ensures cell data in A2 displays 0.00 % .

Two data values 0.00 % or 20.00 % - that is all I needed. I can create formulas to sort and create different tasks, from that point.

Then put in A2:
=IF(A1="UK";20%;0%)

Thankyou Steph1