AI agents for business finance: what they can and can't do
What AI agents can do in bookkeeping, close, collections and compliance today, where a person must stay in charge, and how to judge a product.
The short answer
The effective interest rate is what a loan really costs once fees, timing and compounding are counted, expressed as one rate. It is higher than the headline whenever fees are deducted upfront, interest compounds monthly or the tenor is short. A loan quoted at 2% a month with a 3% fee taken at the start works out, in our example, nearer 2.5% a month, or about 34.5% a year compounded.
Headline rate, nominal rate, effective rate
Lenders in Nigeria quote cost in many ways: '2% monthly', '24% per annum', '15% for 30 days', or a 'service charge'. Each of these is a headline or nominal rate. It tells you the interest charge on paper. It does not tell you how much money you actually received, how quickly you pay it back, or what was deducted on the way. The effective rate puts all of that into one comparable number.
Three things push the effective rate above the headline:
- Fees deducted upfront. If a ₦3,000 fee comes out of a ₦100,000 loan, you have only ₦97,000 to use but repay as though you had ₦100,000.
- Compounding. 2% a month is not the same as 24% a year once each month's interest is charged on a balance that already includes earlier charges. 1.02 to the power of 12, minus 1, is 26.82%.
- Short tenors. A 15% charge for 30 days looks small; repeated across a year, it is very large.
The FCCPC's 2025 digital lending regulations require interest rates, repayment terms and fees to be fully disclosed before a loan is completed (Regulation 17(a)) and rates and charges to be displayed on the lender's platforms (17(b)). The text we read does not require a single annual percentage rate, so working out the effective rate is usually left to you.
Worked example 1: a bank-style instalment loan
Example only. ₦100,000 at 2% a month on the reducing balance, 12 equal monthly repayments, with a 3% management fee deducted on day one.
- Monthly repayment on ₦100,000 at 2% for 12 months: ₦9,455.96 (from the EMI formula or Excel's PMT).
- Cash actually received: ₦100,000 − ₦3,000 = ₦97,000.
- Find the monthly rate at which 12 payments of ₦9,455.96 repay ₦97,000. In Excel: =RATE(12, -9455.96, 97000). Result: about 2.50% a month.
- Nominal annual rate: 2.50% × 12 = about 30.0%.
- Effective annual rate with monthly compounding: (1.025)^12 − 1 = about 34.5%.
The headline was 2% a month, which a reader might call 24% a year. The real cost, once the fee and compounding are counted, is about 34.5% a year. The fee alone added roughly half a percentage point a month.
Worked example 2: a 30-day loan app loan
Example only. ₦50,000 for 30 days, interest 15%, plus a ₦2,500 processing fee deducted from the payout.
| Item | Amount |
|---|---|
| Loan amount | ₦50,000 |
| Paid into your account | ₦47,500 |
| Interest (15%) | ₦7,500 |
| Repaid on day 30 | ₦57,500 |
| Total cost (interest + fee) | ₦10,000 |
| Cost as a share of cash received | 21.05% for 30 days |
| Simple annualised (× 365 ÷ 30) | about 256% |
| Compounded annually | about 922% |
The headline was 15%. The cost on the money you actually had was 21.05% for one month. Whether you think in simple or compounded terms, the annual figure makes clear why rolling such a loan over month after month is expensive. Our guide on working out the APR of a loan app offer takes this method further.
When the fee is added to the loan instead
Some lenders add the fee to the balance rather than deducting it. Example only: the same ₦3,000 fee added to a ₦100,000 loan means you receive ₦100,000 but repay ₦103,000 at 2% a month, or ₦9,739.64 a month for 12 months. You also pay interest on the fee itself. Either way, the test is the same: compare the cash you received with every naira you pay back, and the date of each payment. A fee that looks small next to the principal can be large next to the interest, especially on short loans where there are only a few months to spread it over.
Simple versus compounded annual rates
There are two common ways to turn a monthly or 30-day rate into a yearly one, and you should know which one someone is quoting.
- Simple (nominal) annual rate
- Period rate × number of periods in a year. 2.5% a month × 12 = 30%.
- Effective annual rate
- (1 + period rate)^periods − 1. (1.025)^12 − 1 = 34.5%.
The effective figure is the fairer way to compare a loan you will keep for a year. For a one-off 30-day loan you will clear on time, the cash cost (₦10,000 in example 2) is often the clearest number of all. Use whichever helps, but compare like with like across offers. Our existing explainer on APR versus flat fees shows how fee-based offers compare.
What to check first
- Write down the cash you will actually receive, after every deduction.
- Write down every payment you will make and when.
- Ask whether interest is flat or on the reducing balance; a flat rate has a much higher effective rate than the same number on a reducing balance (see our ₦200,000 comparison).
- Put the cash received and the payments into RATE in a spreadsheet to get the period rate.
- Convert to an annual figure and compare offers on the same basis.
Where Pryme fits
With Loans on Spaces, lent by Solid Allianze Microfinance Bank Ltd and spent only with merchants in Spaces, the agreement shows the amount, the cost and the repayment date before you accept. That gives you the cash figures you need to run the effective-rate check above. See Loans on Spaces.
Questions people ask
What is the difference between nominal and effective interest rate?
Nominal is the quoted rate, often a monthly rate multiplied by 12. Effective counts compounding and fees, so it is usually higher and is the better basis for comparison.
How do I calculate effective interest rate on a loan with fees?
Take the cash you actually receive, list every repayment, and use a spreadsheet's RATE function to find the period rate. Then convert it to a yearly figure.
Is 2% monthly the same as 24% per year?
Only as a simple nominal figure. With monthly compounding it is about 26.8% a year, and higher still if fees are deducted upfront.
Why did I pay more than the interest rate on my loan?
Upfront fees, insurance or management charges, compounding and penalty charges all add to the cost beyond the headline rate. Ask the lender for an itemised breakdown.
Sources
- FCCPC: Digital, Electronic, Online or Non-Traditional Consumer Lending Regulations 2025 · accessed Oct 2026
- Microsoft Support: RATE function · accessed Oct 2026
- Microsoft Support: PMT function · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.