To run a natillera well, you need to record three things with a date and a receipt: each installment, each loan with its repayments and each extra expense or income. With that, the closing distribution is a calculation, not a negotiation.
What to record
| Record keeping | What gets recorded |
|---|---|
| Installments | Who paid, how much, on what day and with what receipt. |
| Loans | Who received it, the amount, the rate, the term and each repayment. |
| Interest and fines | What was charged and to whom, to add it to the fund. |
| Expenses and events | What the group spent and what it raised from bingos or raffles. |
| Closing | Each member’s balance and what they receive in the payout. |
How loan interest is calculated
With interest on the balance, each month’s interest is the balance the member owes times the monthly rate. Example: a $1,000,000 loan at 2% monthly generates $20,000 in interest each month as long as the balance does not go down; over six months that would be $120,000 for the fund.
If the member pays down principal, the balance drops and so does next month’s interest. That is why it pays to record every payment with its date.
Before setting the rate, convert it to an effective annual rate and compare it with the current usury rate: 2% monthly is equivalent to 26.82% effective annual.
How the fund is shared at closing
- Everything in the fund is added up: installments, interest, fines and events.
- The group’s expenses are subtracted.
- Each member’s outstanding loans are deducted.
- The funds are distributed according to the agreed rule. A common rule: interest in proportion to each person’s savings month by month, and event income in equal shares.
Example: two members pay $100,000 a month. Ana saved for all 12 months and Beto joined in month 7, so he saved for 6. The savings-month adds up, month by month, what each one had accumulated: Ana, $100,000 + $200,000 + … + $1,200,000 = $7,800,000; Beto, $100,000 + $200,000 + … + $600,000 = $2,100,000. If the group has $360,000 in interest to distribute, Ana gets $283,636.37 and Beto gets $76,363.63: Ana saved twice as many months, but receives almost four times as much because her savings were also accumulated for longer.
Common mistakes
- Keeping the accounts in one person’s notebook.
- Not leaving a receipt for cash payments.
- Changing the rules halfway through the cycle.
- Working out the payout by eye and discovering differences of a few cents at the end.
- Charging interest above the usury rate.
What to keep them with
BankIA’s natillera calculator simulates how much the fund grows with your installments and loans. NatIA Ahorro keeps this record for you and calculates the distribution with exact arithmetic.
Last updated: October 9, 2026. Written by the BankIA (jsadsAI) team. Educational content: it does not constitute financial or legal advice.
Frequently asked questions
What is “ahorro-mes” (savings-month)?
It is the sum, month by month, of what a person had saved up to that month. It is used to distribute interest fairly: whoever saves more, and from earlier on, receives a larger share.
How often should account statements be provided?
Once a month is enough. What matters is that each member can see their payments, loans and balance whenever they ask.
Can a natillera (a Colombian savings circle) be run in a spreadsheet?
Yes, and many groups start that way. The problem shows up as members and loans grow: formulas break, nobody knows who changed what, and there is no reliable history.
Keep exploring
Natillera calculator
Simulate a natillera: installments, loan interest and how much each member receives at the end of the cycle. Illustrative example.
Open →Usury rate in Colombia
The usury rate is the legal interest cap in Colombia: 1.5 times the current bank interest rate. What it is, who certifies it and where to see the current one.
Open →NatIA Ahorro
NatIA Ahorro handles your natillera’s installments, loans and distribution, with a statement for each member. Per-person pricing in five countries.
Open →Put it into practice with your own data.
Request a demo and we will show you the platform running with your name and your rules.