USDC and USDT are the two biggest dollar stablecoins, and both can be used to fund Polymarket. They do the same job, holding a steady $1 value on a blockchain, but they differ in who issues them, how their reserves are reported and how they’re regulated. This comparison sets out the differences from each issuer’s disclosures and recent reporting, checked October 2026.
Side by side
| USDC | USDT | |
|---|---|---|
| Issuer | Circle (US; listed on the NYSE) | Tether (announced a move to El Salvador in 2025) |
| Reserve reporting | Monthly attestations by a Big Four firm; reserves mostly in a BlackRock-managed government money-market fund | Quarterly attestations by BDO; reserves mostly Treasury bills, plus repo, gold and some bitcoin |
| Size | About $71 billion in circulation (Circle, 26 Oct 2026) | About $185 billion (Q2 2026 attestation) |
| EU (MiCA) | Compliant; issued via Circle’s French e-money licence | Not authorised; major exchanges delisted it for EU users in 2024–2025 |
| US | Circle received a national trust bank charter in 2026 | Tether launched a separate US stablecoin, USAT, in January 2026, issued by Anchorage Digital Bank |
| Polymarket deposits | Accepted on many networks | Accepted on many networks, including Tron |
| Kalshi deposits | Accepted | Not listed in Kalshi’s help materials when we checked |
Attestations check reserves at a point in time; they’re not full audits. Sources: Circle’s USDC and transparency pages, Circle’s 2025 annual report, Tether’s Q2 2026 attestation as reported, and reporting on MiCA and USAT.
Which should you use for prediction markets?
- For Polymarket, either works: Polymarket converts every deposit into pUSD, its USDC-backed trading token. Pick whichever you already hold on a cheap network, and check the minimum for that network on the deposit screen. See Polymarket deposits and withdrawals.
- For Kalshi, use USDC or another asset Kalshi lists; Kalshi credits crypto deposits as dollars.
- In the EU, you may find USDT harder to buy on regulated exchanges because of MiCA.
Risks that apply to both
- Neither is government-insured money; each depends on its issuer’s reserves.
- Both have briefly traded below $1 during market stress.
- Sending either on the wrong network is the most common way to lose funds. Always match networks on both ends.
FAQ
Is USDT or USDC safer?
They differ in disclosure and regulation rather than in a simple ranking: USDC publishes monthly attestations and is MiCA-compliant in the EU; USDT is larger and publishes quarterly attestations. Neither is risk-free.
Can I deposit USDT to Polymarket?
Yes, on many networks. Polymarket converts it to pUSD automatically.
Can I deposit USDT to Kalshi?
USDT wasn’t among the assets in Kalshi’s crypto deposit materials when we checked in October 2026. Check the deposit screen for the current list.
Related: What is USDC? · USDC on Polygon · All crypto guides