There is one rule and it is simple: a cost reduces the base if it is documented and clearly connected to your business. Everything else is detail about applying that rule. Below is the detail, because the detail is what people trip over.
What qualifies without argument
Fuel. The main line. You need a receipt for each refuelling, not a card summary at the end of the month.
Tolls, ferries and paid tunnels are evidenced by the operator’s documents.
Tractor rent. A regular contractual payment — one of the cleanest costs there is from an evidence point of view.
Carrier’s liability insurance. The policy is in your name and relates directly to the business.
Phone and other work services count in the proportion that matches business use — and you have to be able to justify that proportion.
What does not qualify
Fines. Driving-time, speed and overloading penalties all fail the same test — a penalty never reduces the base.
Personal spending on the road. Food, coffee, a shower at a truck stop — those are your costs as a person, not costs of the business, unless there is a separate, properly documented mechanism for them.
Anything without a document. Without paperwork it doesn’t exist as a cost — it’s simply money you spent.
Collect the documents the same day
A receipt photographed at the pump is worth ten minutes in March. A receipt lost last May cannot be recovered by anything.
And separately — the flat-tax regime
On paušální daň this conversation is unnecessary: there are no deductions, no base is calculated, and costs do not affect the payment. In their place is a single fixed monthly payment — in band one, 9 162 Kč.
That is the whole trade, and it is worth seeing in figures: 9 162 Kč leaves the account every month whether you ran a full month’s mileage or sat with an empty tractor. The flat-tax regime as a whole also ends at 2 000 000 Kč of self-employment income, and a driver fits into its cheapest, first band only up to 1 500 000 Kč — road transport carries a 60 % expense allowance, not 80 %.
Sources: Finanční správa press release, 2026 and zákon č. 586/1992 Sb., § 2a.
That is exactly why the choice of regime for a driver with large costs almost always goes to the standard one — the full comparison is in Paušální daň or the standard regime.
