if its haulage taxi bus company then the fuel will be an allowable expense and would generally be shown as a cost of sale.
The cost of sale and motor expenses will both be allowable but just shown in differant locations in the accounts. seperatly showing these costs from general motor expenses will also be useful to allow someone to identify any personal fuel costs for tax return purposes.
Hope this helps.
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Forgive the typo's I generally do not proof read. Just lazy I guess!