In my personal view if things stay like that the “work on the black” will only increase. With manual labor workers this is the most accented because material costs is very small percentage on the overall work, so they can be flexible for huge discounts if paid cash.
Say you have 10k wall painting job, material is 1500 at best, the rest is labor. If we focus on what he could hide, 8500 he needs to pay 8% VAT and probably around 20% tax. You on the other hand could save say 20% as well if you pay the full 10k now and wait couple of years for reimbursement.
Now, both of you come to an agreement for discount of 25% if paid in cash. He gets the same money like before, you get the same as before, only the tax man is left short.
With bigger companies and bigger jobs how it happens is only part of the cost is on invoice the rest is in cash. Say you have a new roof, 120k job. The company issues you a 60k invoice, you give them another 30k in cash. You both save.
Another thing what is done, there is a cap on how much tax you can offset in a year, so what you can do with a friendly company, say you have a year of renovations, they issue you few invoices and spread them through 3 years, say you plan to start in 2025, but the company makes you the invoice for December 2024, June 2025 and January 2026, so you claim to the max in each tax year.
It all depends on how you ask, you have people who are not interested and want nothing to do without invoice, you have a lot of small independents who would save few francs that way.
The way I ask it, in whatever situation, they tell me it would cost this much, I don’t question the sum, but I ask immediately “and how much without an invoice”? My quick math in the head tells me that sum should be -20 to -30% depending on how much material is included.
I once bought a garage door from a huge international company, they had a demo door for sale, already very discounted, the measurements were a perfect fit for me, I tried to haggle, they wouldn’t budge I finally said OK, give it to me without VAT, I don’t need the invoice and they accepted