Fixed costs only affect days within their start/end window — adding a cost today doesn't silently reach back into March. Understanding when and why to backdate is the key piece.
01 What is the fixed-cost lifecycle rule?
See Fixed-cost lifecycle dates for the full rule. The short version: a fixed cost is active on a date if start_date ≤ date AND (end_date IS NULL OR end_date ≥ date). Past days that fall outside the window don't subtract the cost.
02 How do I backfill a fixed cost onto past days?
To make a cost apply to past days, set its start date to when it actually began. If you're adding a fixed cost that should have applied since, say, the start of the year, open Fixed Costs, add the cost, and set the start date to January 1st (or whatever the real start date was). Save, and every day from that date subtracts a slice — your past P&Ls recompute on the next page load. The steps below walk through it.
- 1Open Fixed Costs
Click + Add fixed cost.
- 2Set the start date to January 1st
Or whatever date the cost actually started.
- 3Save
Every day from that start date subtracts a slice of this cost.
Your past P&Ls will recompute on the next page load — they'll now show the new fixed cost in their slice math.
03 Why doesn't nouz auto-backdate fixed costs?
If we auto-backdated every fixed-cost addition, your historical P&Ls would silently change every time you remembered to add a cost. That breaks any reconciliation with your bookkeeper, your tax return, or your own decisions made with the old data. Explicit start dates put you in control.
04 When should I backdate a fixed cost?
Backdate only when the cost was genuinely active in the past — never speculatively. The three cases below cover it: you forgot to add a cost during signup (backdate to your account creation date), you're onboarding mid-year (backdate to January 1st so YTD reflects reality), or a cost has been around longer than nouz has tracked it (backdate to its real start date). Pick the true historical date, not an arbitrary one.
- You forgot to add a cost during signup. Backdate to your account creation date.
- You're onboarding mid-year. Backdate to January 1st so YTD numbers reflect reality.
- A cost has been around longer than nouz has tracked it. Backdate to its real start date.
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