Wise, banks and your LLC: professional banking architecture

Mercury or Wise is too small a question. Build a banking architecture with Relay/Slash, Wise Business and Mercury when it fits, backed by a clean KYC file.

A robust banking architecture for an LLC starts with 3 separate roles: operating account, FX layer and continuity backup with documented KYC.

This isn't an article about Wise vs Mercury (for that you have our <a href="/en/blog/wise-business-for-llc-serious-international-money">complete Wise Business guide</a>, the <a href="/en/blog/mercury-account-for-us-llc-kyc-and-banking">Mercury guide</a> and the <a href="/en/blog/llc-banking-relay-slash-wise-and-mercury">banks vs fintech comparison</a>). It's the article that arranges the previous pieces into a coherent architecture.

The mental error: thinking of the account as "the account"

People coming from Europe or LATAM bring a very specific mental model: one account per person, one account per company. Done. If it gets blocked, you go to the branch, talk to your account manager, fix it. The system assumes the bank has incentives to not lose you as a customer.

In the US fintech ecosystem, that model doesn't exist. Mercury, Wise, Brex, Relay, Revolut Business and friends are technology platforms, not banks. The account is opened by API, closed by API, and decisions are taken by a scoring system + a compliance team you don't know and can't call. If the system decides your account goes under review, your access is frozen for 30, 60 or 90 days, and nobody guarantees you'll recover funds in a short timeframe.

The first mental shift is this: an account is not the account. It's just another vendor, replaceable like a hosting provider or a domain. And like any critical vendor, it needs redundancy.

The minimum viable stack for an operational LLC

From the second year of real activity (i.e. invoicing and collecting regularly), the minimum stack of a well-managed LLC looks roughly like this:

Primary operational USD account (Mercury, Brex or a traditional bank like Bank of America/Chase if you managed to open one in person).
Secondary USD account of the same kind (typically Relay if the primary is Mercury, or vice versa). Not for daily use, but as real failover if the primary gets blocked.
Multi-currency account with European IBAN (typically Wise Business). To collect from European clients in EUR without SWIFT and to have an entry point into the European banking system.
Payment gateway connected to one of the two USD accounts (Stripe, PayPal Business, Dodo Payments). See the <a href="/en/blog/payment-stack-for-llc-stripe-hotmart-and-sequra">payment gateway comparison</a>.
Physical corporate card + virtual cards for SaaS subscriptions and one-off purchases.
Separate reserves for taxes, FX and operations (developed below).

If this looks excessive: it is for month one. It's strictly the minimum to keep operating when something fails. And something always fails.

Why Mercury alone isn't enough

Mercury is arguably the best product on the market for a non-resident's LLC: online onboarding, no monthly fee, decent integration with accounting software and a reasonable support team. But Mercury isn't a bank: it's a software layer on top of partner banks (Choice Financial, Column N.A., Evolve). If one of those partners decides to cut you off, Mercury can't reopen your account or move funds to another partner without your intervention.

What we see at Exentax almost weekly:

Mercury account frozen because of an "atypical" incoming wire (a client from the Philippines, a payment from a crypto exchange, a Stripe return without a clear description).
Automated Mercury email asking for additional documentation (invoice, contract, flow justification).
7 to 14 days without operations while compliance reviews.
In 70% of cases, account restored. In 30%, closure with funds returned in 30-60 days.

If your whole operation depends on that account, during those weeks you can't pay your team, can't invoice clients that require ACH, and can't keep your critical SaaS subscriptions live. Having a pre-authorized and operational secondary account turns a business crisis into a 48-hour annoyance.

Why Wise alone isn't enough

Wise Business is excellent for multi-currency, European IBAN and FX conversion. But Wise isn't a US operational account. Its USD routing and account number are technically "details", not a US-bank-issued nominative account. That has three practical implications:

Stripe US, Amazon US, certain marketplaces and large enterprises accept Wise's USD details without problems, but some (especially public entities, regulated brokers or partners requiring direct ACH) reject them once they detect the receiver is an EMI rather than a bank.
The Stripe → Wise → your local IBAN flow works, but adds another actor to the compliance chain. When there's a freeze, you have to prove full traceability to more than one entity.
Wise reports to your home tax authority via CRS from Belgium and to other jurisdictions depending on where the balance is. If you think Wise gives you privacy, read first <a href="/en/blog/wise-iban-and-llc-crs-holder-and-kyc">what Wise actually reports to tax authorities</a> and <a href="/en/blog/wise-business-and-crs-for-us-llc-owners">how Wise fits into CRS</a>.

Conclusion: Wise is an essential piece of the European puzzle, but doesn't replace an operational USD account nominative to your LLC.

The trap of the Belgian IBAN (and the non-local IBAN)

When you open Wise Business as an American LLC, you get a Belgian IBAN (BE...). This surprises a lot of people who thought they would receive an IBAN from their country of residence. The consequence is twofold:

Operationally, the IBAN works perfectly for SEPA inside the Eurozone. You collect and pay as if it were a Belgian account.
Tax-wise and for foreign asset reporting (Modelo 720 in Spain, IES in Portugal, 3916 in France, equivalents elsewhere), that Belgian IBAN is a foreign account in the name of a foreign entity. If you exceed the thresholds and you're tax resident in one of those countries, you must declare it.

The typical mistake: "since the IBAN starts with BE, it's not 'my account', it's the LLC's, I don't declare it". False. Foreign asset reporting rules look at the beneficial owner (you, the individual), not the formal holder. Same applies to the Mercury account in the US. More on this in <a href="/en/blog/crs-fatca-and-us-banking-privacy-for-llc-owners">US bank accounts and tax authorities</a> and in the <a href="/en/blog/crs-in-spain-and-latam-120-countries-since-2017">CRS guide for residents in Spain and LATAM</a>.

Internal operating rules that save you 5 figures

The stack is just hardware. What avoids real problems are the operating rules you put on top. The ones we recommend to Exentax clients:

1. Never, ever, mix personal and LLC

Sounds obvious, the most expensive and most common mistake. If you pay your personal Netflix with the LLC card, or collect a personal job into the LLC account, you're piercing the corporate veil (the legal separation between you and the LLC) and handing the <a href="https://www.irs.gov" target="_blank" rel="noopener">IRS</a> + your local tax authority a silver platter to treat the LLC as an extension of your personal estate. Zero exceptions. If you need money, you take a distribution and then spend it as an individual.

2. Segment by risk

If your LLC has large B2B clients alongside crypto marketplace payouts or "tier 2" gateway payments, split the flows across different accounts. The primary takes clean, well-documented flows. The secondary absorbs more volatile flows. If the second one gets blocked over an atypical movement, the first keeps running.

3. Tax buffer of 25-35%

Every time money lands in the operational account, automatically separate 25-35% into a "tax reserve" account or sub-account. This covers the tax you'll pay in your country of residence (yes, you will, see <a href="/en/blog/us-llc-federal-tax-residency-and-distributions">why your LLC pays no US tax but you do at home</a>). Mercury and Relay let you create sub-accounts or "vaults"; Wise has "Jars". Use them.

4. Separate FX buffer

If your business invoices in USD but you spend/declare in EUR/GBP/MXN, FX swings can eat 5-10% of margin in a bad quarter. Keep an FX buffer in a multi-currency account so you don't convert at the worst moment.

5. Document contracts before the first payment lands

Every time a >5,000 USD wire from a new client lands, sooner or later you'll get a compliance email asking for "purpose of payment, contract, invoice". Having the contract signed and the invoice issued before collecting (not after) reduces review time from 14 days to 24 hours.

6. Absolute backup: the "what if this falls tomorrow" rule

Ask yourself every quarter: "if Mercury falls tomorrow for good, what do I do in the next 72 hours?". If the answer is "I don't know", the stack is wrong. The right answer is: "I have an operational secondary account, my payment gateway can be repointed in 1 hour, and my critical SaaS provider is on a virtual card from the secondary account".

What happens when they block you (not "if", "when")

Talking about freezes as a rare exception hurts because people don't prepare. Operational truth: every LLC with 18+ months of activity has had at least one freeze or review event. What changes is the magnitude of the damage, and that depends on the stack.

Typical freeze:

Day 0: automated email "your account is under review, please provide additional information".
Days 1-3: you upload requested docs (invoice, contract, beneficiary justification, project screenshot).
Days 4-14: silence. Your access is limited to incoming; no withdrawals or wires.
Day 14-30: either full reopening or closure with funds returned in 30-60 calendar days.

To minimize damage:

Activate the secondary account from day 1, not on the day of the freeze (some onboardings take 2-3 weeks).
Keep both accounts in light continuous use. An account with no activity for 6 months "falls asleep" and sometimes requires re-verification when you need it most.
Save monthly statements as PDF in your own drive. If they close you, you may lose access to the UI but still need those statements for tax and accounting.
Document each client with a mini-dossier (website, contract, legal address). Compliance teams appreciate it and your response time drops.

The gateway conversation: Stripe and friends

Stripe is the default option for almost any LLC, but it has its own freeze regime: rolling reserves of 5-10% for 90-120 days for new or high-risk accounts, and the possibility to freeze funds on fraud or high-dispute detection. Basic rules:

Don't connect Stripe to a single account. If Stripe sends a payout and the receiving account is blocked, money goes into limbo.
Set your Stripe descriptor to your real commercial name (not the LLC legal name) to reduce "I don't recognize this charge" chargebacks.
If you take recurring subscribers, configure churn alerts + a buffer equivalent to 30 days of payout to absorb a freeze.

PayPal Business is useful but has a deserved reputation for arbitrary freezes. As a complementary channel it works; as the only channel, no.

Cards: physical, virtual and the "one per category" rule

Cards are the most overlooked piece. Operational recommendation:

One physical card: for physical spend (coworking, travel, client meals).
"SaaS" virtual card: all recurring subscriptions. If compromised, you stop one set of charges only.
"Ads" virtual card: paid campaigns (Google Ads, Meta, LinkedIn). High and unpredictable spikes that wake up anti-fraud.
"Single-use" virtual card: one-off purchases from less-trusted vendors. Generate, use, close.

Mercury and Brex issue all these categories at no cost. Wise too. If you pay everything with the same card, a single fraud takes down your whole operation.

A banking stack needs roles, not account accumulation

The right question isn't "Mercury or Wise", it's "what stack do I build".
A professionally operational LLC has at minimum 2 USD accounts + 1 multi-currency account + gateway + segmented cards + reserves.
Mercury alone isn't enough. Wise alone isn't enough. Both combined still aren't enough without reserves and rules.
The Wise IBAN is Belgian, not local. Still a foreign account for reporting purposes.
Freezes are not exceptions, they're a routine event with a predictable timeline. The difference between "annoyance" and "crisis" is the stack.
Never mix personal and LLC, segment by risk, 25-35% tax buffer, FX buffer and pre-payment documentation are the five rules that reduce banking, tax and operational exposure.

If you have an LLC and want us to design the right banking stack for your volume and risk profile with you, we'll go through it together in a strategic 30-minute review. Building it well is cheap. Building it half-way and finding out the day Mercury sends the first "your account is under review" email is expensive.

Assign one role to every financial provider

Wise, a US bank and a fintech do not play the same role; the architecture is decided by collections, FX, backup and reporting:

Mercury: use it as a US-account layer only when it complements the rest of the stack; it should not duplicate the role of Wise, cards, reserves or platform payout accounts.

Give every account one documented purpose

The LLC banking stack reads more usefully when it's treated as a stable mapping between operational role, holder of the account and country of the IBAN, than as an open product comparison. Within the providers that are operationally compatible with US LLC profiles — Mercury, Wise, Stripe and Relay — each one occupies a discrete role: Mercury and Relay as the LLC's US operating account, Wise as the multicurrency layer, and Stripe as the merchant ingest where applicable.

A short note in the LLC folder that records which provider plays which role in the current stack, with the date the configuration was set, makes the architecture reviewable in a few minutes whenever a counterparty asks for a payment instruction or a tax adviser asks for a reconciliation.

The same note also makes it much easier to spot when one of the providers stops fitting the role it was assigned and another configuration is needed, instead of waiting for a friction event to discover it.

> <a href="/en/book">Review my structure</a>

A mature banking stack is not a random collection of accounts. Each provider should have a role: collections, reserves, FX, cards, payroll, brokerage or backup. That clarity is what makes the stack resilient when compliance questions arrive.

The regulatory perimeter of each account

The banking stack should be chosen from the company’s real flow: currency, clients, payout platforms, owner residence, expected wires and compliance story. A good stack is the one a reviewer can understand quickly.

_More on this topic: LLC in the United States: complete guide for non-residents._