It is better to obtain an invoice when purchasing items for the business. An invoice will include your VAT number, name, the amount and related VAT. VAT-deduction is only possible based on solid invoices mentioning your name, VAT-number, address. Cash receipts, tickets, notes never allow VAT-deduction. When there is no VAT to deduct (public transport, post office, etc) this is less a concern of course, but an invoice (if possible to get one) is still and always a much better accounting evidentiary record providing tax proof of the expense. For small ticket items we can appreciate that you will not wait a long time to obtain an invoice. But for substantial amounts, the payback is worth the wait.
When choosing local providers, please inform them of your VAT-number before signing up (mobile phone, utilities, subscriptions, possibly cable TV).
If an invoice is unavailable (travel expenses) keeping your email confirmation, boarding pass, credit card statement / payment justifies and documents the expense. All of this can be forwarded to Leuven Accountants as official accounting records.
In reference to Fuel Cards
It is to your benefit to find a local petrol or fuel card provider. Note that some work internationally (but might be more expensive) and others only work in Belgium. Why? Because the Belgian tax authorities do not accept VAT-deductions from the small receipts from the petrol stations. Also these bi-weekly or monthly statements provides a detailed fiscal record of your petrol purchases. There is no longer a need to keep the small tickets once you have obtained a fuel card.