Interesting. Would you care to enlighten us on a legal way to do this ?
Of course, the parent may also have been referring to getting clients to pay in cash and not putting anything on the books, at the expense of getting barely any pension in the end, but that's not how I read it. This is getting somewhat less common because people are more likely than 20 years ago to get a loan from a bank to pay for renovation work, and the bank will want to see invoices.
Just to be clear, if you're a VAT-registered tradie doing a job for yourself, you are obligated to pay VAT for the materials. Diverting vat-reclaimed materials for self-supply is tax evasion (which can be identified by auditing invoices). So legally speaking, the only money saved is the VAT on your own work hours.
Slightly ironically, self-supply is much easier and almost impossible to identify when devs use work-paid subscription services (e.g. Claude Max) on personal side hustles.
If a Norwegian tradesman works on his own home, he's supposed to pay VAT on the value of the work he's done - not only on the materials used.
I suspect such work is being under-reported, though.
