For both borrowers and lenders, it is essential that the monthly installment to repay a loan can be paid. In order not to overburden the borrower with the sum, a "burden ratio" is calculated.
The burden ratio is expressed as a percentage and is the proportion from the monthly installment in relation to the allowance. The lower the burden ratio, the more financial leeway the borrower has.
The Consumer Credit Act (KKG) stipulates that the maximum burden ratio for repayments over 36 months is 100%.
By the way: In the case of married couples, the exemption amount of the total income is used, as it is assumed that the expenses are borne by both spouses.