Walkthrough · article 12 of 18

Updating a fixed cost.

Why a rent increase doesn't backdate. End the old cost, start a new one — here's the two-step pattern.

Ibrahim Ölmez Ibrahim ÖlmezFounder · nouz · 5 min read · Updated this week
The principle. A fixed cost's amount + frequency is a snapshot of what it cost on the day you logged it. To change the amount going forward, end the old cost and start a new one — don't overwrite history.

Updating a fixed cost uses the same pattern as retiring one: end the existing version, start a new version. This protects every past P&L from silently recomputing when reality changes — your March numbers always show March's rent, even after October's rent bump.

01 Why no in-place edit

If we let you change the amount on an existing fixed cost, every past day's P&L would silently recompute against the new number. Your March P&L (when rent was €2.800) would suddenly show €3.000 of rent because you signed a new lease in October. That's a lie about the past — and it breaks any reconciliation with your bookkeeper.

02 The two-step pattern

  1. 1
    End the old cost

    Open the existing fixed cost. Set its end date to the day before the change.

  2. 2
    Add a new cost

    Click + Add fixed cost. Name it the same thing, type the new amount, set the start date to the day of the change.

  3. 3
    Save

    Past days subtract the old amount. New days subtract the new one. Past P&Ls stay honest.

03 When in-place edit is fine

For cosmetic changes — fixing a typo in the name, adding a note — editing in place is fine. The amount and frequency are what trigger the recommend-replace pattern. nouz nudges you when it spots an amount or frequency edit on a fixed cost that's been active for more than seven days.

04 Common scenarios

Three real-world cases that use this pattern:

  • Rent increase. Lease renewal raises rent from €2.800 to €3.000 on January 1st. End the old line on Dec 31, start the new line on Jan 1.
  • Switching providers. Old internet at €95/month, new fibre at €120/month from October 1st. End the old line, start the new line — could keep the same "Internet" name or distinguish "Internet (DSL)" vs "Internet (fibre)".
  • Adding a part-timer. Base staff cost was €7.200/month, now you're adding €1.200 for a Saturday helper starting March. Two options: end the old "Staff" line and start a new "Staff" line at €8.400, or add a separate "Saturday helper" line at €1.200. The second is more readable for future you.
The "same name" trick is cosmetic. You can name the new fixed cost the same thing as the old one for visual continuity in the list. It's a separate row in the database — the name is just a label.

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Still stuck? Email support@nouz.co — a founder replies, usually the same business day.