1. Definition
The cost-to-income ratio divides a bank's operating expenses by its net banking income (NBI). It says what share of what the bank produces goes into running the bank itself.
Operating expenses group three items: staff costs, general operating expenses and depreciation.
In French, it is called the coefficient d'exploitation.
2. The measure
One formula, the same for every bank: staff costs, plus general operating expenses, plus depreciation, divided by NBI for the half-year.
Example, the bank with the lowest ratio: BT, in the first half of 2026: its operating expenses absorb 34.6% of its NBI.
The lower the ratio, the more income is left to cover risk and produce a profit.
3. Why it matters
It is the measure of a bank's efficiency. Two banks with the same NBI can earn very different profits depending on what their network, teams and systems cost them.
It moves slowly. Operating expenses are set over several years (hiring, branches, IT); a ratio that falls for good says a bank that produces more without growing as much.
4. What it does not say
It does not say whether the bank invests. A high ratio can come from a network being modernised, and a low one from investment put off.
It says nothing about risk. The cost of risk is read below NBI, after operating expenses; an efficient bank can lose its lead on provisions.
5. Where to read it in Tunisian financial statements
The three items of operating expenses are read in the income statement: CH6, staff costs; CH7, general operating expenses; CH8, depreciation of fixed assets. NBI is read there too, as total banking operating income less banking operating expenses.
The amounts are taken as published, for the half-year.
6. Three reading traps
First trap: fast-rising NBI lowers the ratio without the bank spending less. Both movements must be read, not only the ratio.
Second trap: a bank can keep some costs out of its operating expenses (outsourcing booked elsewhere, exceptional charges). The ratio compares banks that present their accounts the same way.
Third trap: over a half-year, a one-off charge (a severance payment, a campaign) can move the ratio by several points. It is followed over several periods.
7. Ranking of the 10 listed banks by cost-to-income ratio, first half of 2026
The banks are ranked from the highest value to the lowest, amounts in millions of dinars:
| Rank | Bank | Operating expenses (TND m) | NBI (TND m) | Cost-to-income ratio |
|---|---|---|---|---|
| 1 | ATB | 139.0 | 187.0 | 74.3% |
| 2 | UBCI | 126.0 | 194.9 | 64.7% |
| 3 | STB | 188.1 | 313.7 | 60.0% |
| 4 | UIB | 148.2 | 273.8 | 54.1% |
| 5 | Attijari Bank | 190.7 | 374.8 | 50.9% |
| 6 | BH Bank | 163.1 | 345.7 | 47.2% |
| 7 | BIAT | 372.3 | 802.7 | 46.4% |
| 8 | BNA | 213.0 | 560.1 | 38.0% |
| 9 | Amen Bank | 128.0 | 362.4 | 35.3% |
| 10 | BT | 101.1 | 292.1 | 34.6% |
Definitions NBI
Out of scope: BTE (preferred dividend shares) and Wifak International Bank (an Islamic bank).
The cost-to-income ratio ranges from 34.6% to 74.3% depending on the bank. Across the 10 banks together, operating expenses take 47.7% of NBI.
Key points
- Cost-to-income ratio = staff costs, general operating expenses and depreciation, divided by NBI.
- The lower it is, the more income is left for risk and profit.
- It is read with the movement of NBI and expenses, and over several periods.
Read also: cost of risk of a bank, the half-yearly note on listed banks, the method of the series.
Sources: interim individual financial statements at 30 June 2026 published with the Conseil du marché financier (CMF), notes included.