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Fiscal deductibility of vehicle costs in Muto

What is tax deductibility of car expenses?

Tax deductibility determines which part of your car expenses is deductible in corporate income tax.

In Belgium, specific rules apply to passenger cars. The deductible percentage depends on the vehicle’s characteristics and the relevant reference date. For other assets (e.g. LCVs) and non‑Belgian vehicles, Muto applies 100% tax deductibility by default.

Key points

  • Applies to: Passenger cars with country of registration = Belgium

  • Time‑based: the percentage can change over time

  • Determined by: CO₂ emissions, powertrain, legal regimes, and reference dates

  • Muto automatically shows and uses the correct percentage per cost line

Belgian legislation: concepts and logic

1) Time dependency: percentage per booking date

The legal deductibility is time‑based: for each cost, the percentage that applies is the one linked to the booking date.

One vehicle can therefore have multiple periods with different percentages. Muto stores this in a timeline and applies the correct rate to each cost line.

2) Parameters that determine deductibility

The most important parameters are:

  • CO₂ emissions and powertrain
    (e.g. petrol/diesel, PHEV, electric)

  • Country of registration
    (the Belgian rules apply only to vehicles registered in Belgium)

  • Reference dates (see below): e.g. order date, first registration date, contract start date, or other dates defined by the user

3) Contract extension and “matrix contract”

The tax regime that follows from the order date remains valid as long as all contract parameters are explicitly known and documented.

In case of a silent extension (without reconfirming the parameters), a new tax regime may become applicable.

However, when a matrix is defined on the contract (so that all parameters remain known even after the official end date), a silent extension is not considered a change, and no new tax calculation is required.

How Muto calculates tax deductibility

1) Entry point in the menu

On the asset detail page (for Belgian vehicles only) you will see a tile “Fiscal deductibility”.

When you click this tile, a drawer opens showing:

  • Vehicle parameters that influence deductibility (country, CO₂, powertrain)

  • The set of reference dates used for the calculation

  • A table with periods and their related deductibility percentages (only the change points)

2) Managing reference dates

  • Default reference date when a vehicle is created: the order date.
    If that is empty, Muto uses the first registration date.

  • You can add extra reference dates to recalculate the fiscal regime, for example:

    • at the start of a new contract

    • when transferring a vehicle between companies

  • After you save a changed set of reference dates, Muto:

    • requests a new timeline from our fiscal calculation service, and

    • recalculates all non‑fixed costs

3) Application to costs and disallowed expenses

For each cost, Muto determines:

  • the tax deductibility rate, based on:

    • the asset (type and country of registration)

    • the booking date (matched to the right period in the vehicle timeline)

    • the fiscal interpretation of the cost type (see below)

  • the disallowed expense, calculated as:

(Cost amount + non‑recoverable VAT) × (100% − deductibility percentage)

Muto automatically calculates these values for each cost line.

Fiscal interpretation per cost type (Belgian rules)

In Muto, the field “Fiscal Interpretation (BE)” on the cost type defines how the deductibility percentage for that cost is calculated or limited. There are three categories:

1) Standard

  • The deductibility is taken directly from the vehicle timeline (per booking date).

2) Fossil Fuel

  • For passenger cars with:

    • order date after 31/12/2022, and

    • powertrain = PHEV (PHEVP or PHEVD)

    certain cost types have a maximum of 50% deductibility.

  • If the vehicle itself has a lower deductibility than 50%, the lower vehicle percentage applies.

  • If the vehicle is more than 50% deductible, it is capped at 50% for these costs.

3) Fully Deductible

  • These costs are always 100% deductible, e.g.:

    • interest

    • general mobility

    • public transport

Where do I find this interpretation?
The fiscal interpretation is part of the cost type configuration in Muto and is used by the cost engine to determine the correct tax deductibility and disallowed expenses.

Examples and practical cases

Case A — Standard maintenance cost

  • Vehicle: Belgian passenger car, CO₂ = 120 g/km

  • Cost type: MAIN (General Maintenance) → Standard

  • Booking date: falls in a period with 67.5% deductibility

Result

  • Cost deductible at 67.5%

  • Disallowed expense = (net amount + non‑recoverable VAT) × 32.5%

Case B — PHEV fuel cost after 31/12/2022

  • Vehicle: Belgian passenger car, PHEV, ordered on 15/02/2023

  • Cost type: FUEL (Fossil Fuel) → Fossil Fuel

  • Vehicle timeline: 80% standard deductibility, but Fossil Fuel has a cap

Result

  • Deductibility for this cost = 50% (capped)

  • Disallowed expense = (net amount + non‑recoverable VAT) × 50%

Case C — Interest cost

  • Cost type: INTE (Interest) → Fully Deductible

Result

  • Always 100% deductible

  • No disallowed expense on this cost line

Limitations and scope

  • Muto does not provide detailed legal explanations of each legislative change in the user interface.

  • Muto does not automatically add extra reference dates; managing reference dates is the user’s responsibility.

  • The calculation logic for the percentages is handled by our fiscal calculation service; Muto consumes the resulting percentages.

  • For non‑Belgian assets, Muto assumes 100% tax deductibility.

  • VAT deductibility is handled separately and is outside the scope of this article.

Best practices for fleet and finance teams

  • Maintain reference dates whenever contract conditions change
    (new contract start, transfer, explicit parameter changes).

  • When cost results look unexpected, check the timeline in the “Fiscal deductibility” drawer.

  • Choose the correct cost types: this determines whether a cost falls under Standard, Fossil Fuel, or Fully Deductible.

  • Approval flow: approve invoices only when:

    • the correct vehicles are linked, and

    • all relevant data is complete,
      so that deductibility and disallowed expenses can be calculated correctly.

Frequently asked questions

When do I see the “Fiscal deductibility” tile on my vehicle?
The tile appears only for vehicles with country of registration = Belgium.
For non‑Belgian assets, Muto does not show this tile and treats costs as 100% deductible.

What if my cost date falls outside the known periods?
Muto applies the following rule:

  • If the booking date is before the first known period, the oldest known rate is used.

  • If the booking date is after the last known period, the most recent rate is used.

Can I override the percentage manually?
No. You manage the reference dates. Based on those dates, our fiscal calculation service recalculates the official percentages, and Muto applies them automatically.

What happens after I change reference dates?
Muto requests a new fiscal history from our fiscal calculation service, replaces the previous table, and recalculates all non‑fixed costs (including deductibility, fiscal reference date on the cost, and disallowed expenses).

How does Muto handle “Fossil Fuel” costs for PHEVs ordered after 31/12/2022?
These costs are limited to a maximum of 50% deductibility.
If the vehicle’s own deductibility is lower than 50%, Muto uses that lower rate.
If it is higher than 50%, Muto caps it at 50%.