Savings circles on Arc
Everyone pays in. Everyone gets a turn.
A group, a fixed amount, one pot that goes around. The tanda your family has always run, now in dollars on Arc, with the pot held by a contract that only pays whoever's turn it is. Nobody can run off with it. Not even the organizer.
USDC or EURC2 to 30 peopleless than a cent per payment
One idea, everywhere
It has a hundred names
Economists call it a rotating savings and credit association, a ROSCA. (Rosca is Spanish for a ring, which fits.) Wherever you grew up, it probably had its own name:
tandaMexico/ cundinaMexico/ cuchubalGuatemala/ juntaPeru/ panderoPeru/ consórcioBrazil/ pardnaJamaica, UK/ susuGhana, Caribbean/ esusuNigeria/ tontineSenegal, Cameroon/ njangiCameroon/ likelembaCongo/ stokvelSouth Africa/ xitiqueMozambique/ chamaKenya/ equbEthiopia/ hagbadSomalia/ gam'eyaEgypt/ dartMorocco/ günTurkey/ kametiPakistan/ chit fundIndia/ dhikutiNepal/ seettuSri Lanka/ chaeThailand/ kootuMalaysia/ arisanIndonesia/ paluwaganPhilippines/ huiChina, Taiwan, Vietnam/ gyeKorea/ tanomoshiJapan/ moaiOkinawa/ menodgeScotland
Everybody puts in the same amount every week or month, and each time one person takes the whole pot. It gets people a lump sum without a bank, without interest and without a credit check.
It runs on trust, and that's also where it breaks: the organizer who disappears with the money, the cousin who collects first and then stops paying.
Names from Wikipedia's list of ROSCAs by country. On the economics: Besley, Coate & Loury, “The Economics of Rotating Savings and Credit Associations”, American Economic Review, 1993.
How a tanda works
Five people, $100 a week
Work tanda · $100 a week
| Number | Wk 1 | Wk 2 | Wk 3 | Wk 4 | Wk 5 |
|---|---|---|---|---|---|
| 1Rosa | $500 | ||||
| 2Beto | $500 | ||||
| 3Lupe | $500 | ||||
| 4Chuy | $500 | ||||
| 5Ana | $500 |
Each of them puts in $500 over five weeks and each takes out $500.
Rosa, number one, gets hers right away, which is really a loan from the other four. Ana, number five, waits until the end, which is really saving. Nobody pays interest and nobody earns any.
- Someone sets it up.
How much, how often, how many people and how much protection. That's the whole form.
- Everyone picks a number.
Your number is your turn. Number 1 collects in the first round, number 2 in the second, and so on.
- Every round, everyone pays.
The moment the last person pays, the pot goes to that round's number. Nobody has to press anything.
- The last number collects and it's over.
Deposits go back to their owners and the tanda closes. Another round? Start a new one.
Why on Arc
What changes when the pot lives on Arc
The pot has no keeper
Each tanda is its own small contract. Money comes in from the members and goes out to the number whose turn it is. There is no button, for the organizer or for us, that sends it anywhere else.
The notebook can't be rewritten
Every payment is on Arc's public ledger. The whole group can see who has paid, who's late and who's next, like the organizer's notebook, except nobody can tear out a page.
Fees are in dollars, and tiny
On Arc you pay network fees in USDC, not in some other token. Paying your share costs less than a cent, and a whole ten-person tanda costs the group well under a dollar.
Dollars or euros
Run it in USDC or in EURC, both issued by Circle. If your money is on another network, you can bring it over to Arc in a few minutes.
The honest part
What a contract can't do
A contract can make sure the pot goes to the right person. It can't make someone keep paying after they've collected. That part is still about trust, same as always.
So there's a deposit. When you set up a tanda you choose how much protection it has, from 0 to 100%. The early numbers collect before they've finished paying in, so they put down more. The last number puts down nothing: by the time they collect, they've already paid everything.
If someone is late, their deposit covers the round and the pot still goes out whole. If the deposit runs out, whoever came up short is owed the difference and gets paid first from anything the late person pays back, including their own pot if their turn hasn't come yet. And it stays on their record.
The token
TANDA, and what it does
There is a token, and this is everything it does: if you hold at least a set amount of TANDA when your turn comes, you collect your pot without the 0.5% fee.
It isn't a share of anything. It doesn't pay dividends, and nobody's promising it goes up. The app works exactly the same without it.
- Network
- Arc, chain 5042
- Ticker
- TANDA
- Contract
- Not launched yet. It will be posted here and on our X account. Any TANDA contract that isn't on this page is a copy.
- Fee waiver
- A set amount of TANDA or more when you collect
- App fee
- 0.5% of each pot, fixed per tanda, never above 1%
Questions
Before you start one
What do I need?
A wallet that works with Arc (MetaMask, Rabby and most EVM wallets do) and some USDC or EURC on Arc. Keep a few cents of USDC for network fees: on Arc, fees are paid in USDC.
Who can see and join my tanda?
Anyone with the link can see it, and anyone can find it on the explorer. Anyone with the link can also take a free number. The organizer can take people off the list before it starts, and once it starts the list is locked. Names are optional and public, so use a nickname if you'd rather.
What if I lose access to my wallet?
Your number is tied to your wallet address. Nobody can redirect your pot, not the organizer and not us, so keep your recovery phrase somewhere safe. Someone else can still pay your share for you.
Can I leave?
Before it starts, yes, and your deposit comes straight back. After it starts, no: leaving halfway hurts everyone who comes after you, same as in any tanda.
What does it cost?
Network fees of a fraction of a cent per payment, plus 0.5% of each pot when it's collected (nothing if you hold TANDA). The fee is fixed when the tanda is created and can never go above 1%.
Is this a bank? Does it lend money?
No. Tanda is software. It doesn't lend, invest or hold anyone's money: each tanda's contract does, under rules anyone can read. Rules for savings groups vary from country to country, so if you run big ones, check yours.
Who made this?
A small independent team. We're not Circle and we're not affiliated with them; we just think Arc is a good place for this. The contracts are open, so you can read them on the explorer.
Has it been audited?
Not by an outside firm yet. The code is short, has no admin keys over your money, and is tested for late payments, defaults and blocked addresses. Still, start with amounts you're comfortable with.
Start one with people you trust
You'll need a wallet on Arc and a few dollars in USDC. Setting it up takes a couple of minutes; the hard part is still picking the group.