The trap of mental linear math

"If I go from €600/day to €650/day, I'll earn an extra €50 × 200 days = €10,000."

Wrong. Or rather: not really. Because between social charges, VAT, and income tax (or corporate tax if you're in a SASU), you don't actually see that whole gap on your personal account.

The honest math, for a SASU at 45% charges and 30% income tax:

  • +€50 × 200 days = +€10,000 gross revenue
  • Minus 45% social charges on the new pay = ~€5,500 net to pay yourself
  • Minus ~30% income tax = ~€3,850 actually landing on your personal account

You earn about €3,850 a year, not €10,000. Still good to take, but it changes the negotiation strategy: worth pushing, but maybe not worth the clash.

Why what-if scenarios change the game

Instead of doing this rough mental math, you let an engine handle it:

  • Take your current situation
  • Change a single parameter (rate, days/month, charges, expenses)
  • See the impact instantly on:
    • Annual gross revenue
    • Monthly net profit
    • Margin
    • 12-month cashflow
    • Runway

Three scenarios to test before every renegotiation

Scenario 1 — The minimum acceptable

What day rate do you need to hit your personal targets (€3,500 net/month in SASU, for example) while working 18 days a month and keeping 2 months of runway after charges?

The engine gives you the number. That's your negotiation floor.

Scenario 2 — The realistic

The market-average day rate for your profile. The engine tells you: with this, I earn X net, I can save Y a month, my margin drops to Z%.

That's your target.

Scenario 3 — The optimistic

If you could really push and land the top of the market. The engine shows you what it looks like in 12-month cashflow. That's your ceiling — often higher than what you'd dare ask.

The reverse: what if it drops?

Equally important: what happens if you have to accept −€50/day because your client claims a tight market?

Over 200 days, you lose €10,000 gross. After charges and taxes, that takes about €3,850 off your personal account — ~€320/month.

If your 12-month treasury projection drops from a health score of 82 to 68, and runway from 5 months to 3, it's probably a polite "no". Otherwise you can accept, knowing exactly the cost.

The moment you commit

The practical rule: always run the scenario before the conversation.

Not after. Not "I'll see how it goes and crunch numbers later."

You walk into the negotiation with your floor, your target, your ceiling. And critically: you know why. When the client says "€600 is too high, we're at €550", you know €550 costs you 2 months of runway over the year — so it's a no. At €580, you keep your margin, so OK.

That's what a what-if scenario gives you: the confidence of a numerical answer rather than a gut feeling.

What it actually changes

Without scenarios: you renegotiate roughly every 18 months on average, you leave money on the table because you ask for "a bit more" without knowing how much it really is.

With scenarios: you renegotiate every 9-12 months, with a precise range, and you know how to say no without guilt when the client is below your floor. You also know how to accept quickly when an offer is above your target — without dragging your feet out of fear.

A freelancer who masters their scenarios grows revenue by 10-15% per year on average. Not by luck — by method.