Costs incl./excl. VAT

I would like to enter the purchases of the course at the Centre for Evening Education as expenses. I purchased this course because I needed the diploma to be able to start. I purchased it before I had not started as a self-employed person. I paid the amount incl. VAT as a private person. When entering the expenses, you also have to enter the amount excl. VAT. Can I calculate this myself? 21%?