It depends on who the lender is and certain limits
If you take out a (mortgage) loan or lease with a bank or an external third party to finance a business purchase 💰 there is no limit on deductibility (apart from the % of business use if you are an individual financing a car, for example).
On the other hand, if your company borrows from its shareholder/manager or from the latter's spouse, cohabitant or child, limits apply:
The amount of the interest-bearing loan cannot exceed: taxed reserves at the start of the accounting period + tax-paid-up capital at the end of the accounting period.
The maximum rate is that charged on the market for a loan with the same characteristics (amount, term, risk, etc.), except in the case of a non-mortgage loan with no term. In this case, the rate is set by the NBB (4.07% for interest relating to 2021).
💡 If you're in a company and want to be sure about the deductibility of interest on your loans, discuss it with your accountant! An analysis is a must!