The First 90 Days After US Company Formation: What UK Founders Need to Do Next

Forming your U.S. company is only the beginning. The first 90 days are where UK founders either build a clean, workable setup or create admin problems that are painful to fix later.

Setting up a U.S. company can feel like the hard part. You choose the state, file the paperwork and wait for confirmation. Then comes the surprise. You are still not fully operational.

For founders trying to start an LLC in the USA, the temptation is to treat approval as the finish line. In reality, it is only the start. You still need an EIN, a workable banking plan, proper bookkeeping, a filing calendar and a clear understanding of what has to be done even if the business is not yet trading. That is why US business registration should be treated as the start of the process, not the end.

This guide breaks down what to do in the first 90 days after US company formation, especially if you are managing everything from the UK.

Useful read: A UK Founder's Guide to Registering a Company in the US

Why the first 90 days matter so much

A lot of founders think company formation is the finish line. In reality, it is the starting point.

Your company may exist on paper, but that does not mean it is ready to open a U.S. bank account, invoice clients properly, stay on top of federal and state filing deadlines, handle bookkeeping correctly and grow into more than one state without problems.

That gap between “formed” and “fully set up” is where a lot of avoidable mistakes happen.

If you are a UK founder, distance makes this harder. You are dealing with U.S. rules from overseas, different state requirements, banking checks and tax systems that do not work like HMRC. That is exactly why the first 90 days need a plan rather than a pile of disconnected tasks.

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Days 1 to 14: Make sure your core setup is actually usable

The first two weeks are about getting your foundation in order.

That means confirming more than just the fact that your company was approved. You need to make sure the structure, documents and addresses you are using will actually support the next steps.

Start with these basics.

1. Save your formation documents in one secure folder.

2. Confirm your entity type and state are still the right fit for how you plan to operate.

3. Make sure your registered agent is in place.

4. Review the address you are using for business records and banking.

5. Prepare the internal documents your business may need, such as an operating agreement or bylaws.

This matters because the wrong structure, the wrong address setup or missing internal documents can slow down everything that follows. It is far better to review these details early than to fix them after a rejection from the IRS, a bank or a platform.

Useful read: The 10 Best State for LLC Formation for UK Founders in 2026

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Useful read: Your Free Operating Agreement Template for LLC Formation

Days 7 to 21: Apply for your EIN properly

Once your entity is formed, one of the next critical tasks is getting an EIN.

For UK founders, this step often looks simpler than it really is. If you are applying for a US

EIN for a UK business, accuracy matters more than speed. Errors can delay the process and those delays can slow down everything that comes next.

That matters because without an EIN, many other steps stall. Bank account opening, payment processor onboarding, payroll setup, tax registrations and accounting system configuration all become harder.

Common mistakes include using inconsistent business details across documents, misunderstanding who should be listed on the application, using an address that creates verification issues, assuming the process works the same way for non U.S. founders as it does for U.S. residents and filing before the formation details are fully confirmed.

A delay of a few weeks may not sound dramatic, but it can hold up your banking, your client onboarding and your ability to trade properly.

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Days 15 to 30: Build your banking plan before the problem appears

A lot of founders treat banking as a simple admin step after formation. It is often one of the most frustrating parts of the whole process.

Different banks have different requirements for non resident founders. Some may want extra proof of address or business activity. Some may be comfortable with one setup and others may not. That means the right question is not just “Which bank should I try?” It is “What evidence will this bank expect from a UK founder like me?”

Before you apply, gather your formation documents, EIN confirmation, founder identification, details of your business address, any supporting proof the bank may request and a clear explanation of what the business does and where it operates.

If your plan depends on a virtual address, a basic mailbox or a last-minute document scramble, there is a good chance your application will slow down.

Useful read: Best us bank accounts for UK entrepreneurs: Open your US business account in 2026

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Days 21 to 45: Set up your accounting and tax systems early

This is where many founders wait too long.

They assume accounting can be sorted once revenue starts coming in. In practice, that delay creates mess, mixed transactions, incomplete records, missed filing questions and poor visibility over what the business is doing.

Setting up your accounting and tax systems early helps you stay organised from the start.

That usually means choosing software such as QuickBooks or Xero, putting a bookkeeping routine in place, understanding your federal and state tax obligations and making sure you stay on top of ongoing compliance. Even if your U.S. company is not yet trading, some filings and annual reports may still be required.

By around the first month, you should have accounting software selected, a bookkeeping process agreed, business transactions separated clearly from personal ones, a way to track expenses, invoices and receipts and an early view of your likely federal and state filing obligations.

Useful read: US Cross Border Tax Planning for UK Founders

Days 30 to 60: Understand your compliance calendar

This is the stage where founders need to stop thinking only about setup and start thinking about maintenance.

U.S. compliance can be strict. Annual reports, federal filings and foreign ownership reporting can still matter even when a business is inactive. Missing a required filing can lead to penalties and can create problems with banks, state good standing and future growth.

That is exactly why the first 60 days should include a proper filing calendar.

Add these to your compliance tracker.

1. Annual report due date in your formation state

2. Federal filing deadlines

3. Any foreign ownership reporting requirements

4. Registered agent renewal dates

5. Accounting close and review dates

6. Sales tax review points if you are selling in the U.S.

A simple rule to follow is this. Do not assume “inactive” means “nothing to file.”

Informational disclaimer: This article is for general informational purposes only and does not constitute legal, tax or accounting advice. Filing obligations vary by state, entity type and ownership structure, so you should take advice based on your specific circumstances.

Days 45 to 75: Pressure test your setup for how the business will really operate

Once the essentials are in place, the next question is whether your structure still makes sense for your real trading plans.

This is the point where growth decisions start to affect compliance.

For example, will you sell into multiple states, hire U.S. contractors or employees, need payroll, create nexus in places you did not expect or find that your current state choice no longer makes sense once the business grows?

Imagine a UK ecommerce founder forms a U.S. LLC and opens the company successfully. In month one, everything looks simple. By month three they are selling into several states, they start using a U.S. fulfilment partner, they hire a U.S. based contractor and they assume tax and compliance are still only about the formation state.

That is where problems begin.

Growth changes the compliance picture. A company that looked simple on day one can become multi state surprisingly quickly. That is why the first 90 days should include a growth review, not just formation admin.

Useful read: Operating in More Than One US State? What UK Founders Need to Know Before It Becomes a Compliance Problem

Days 60 to 90: Move from setup mode into operating mode

By the end of the first 90 days, you want to be in a position where the company is not just formed, but workable.

That means you should be able to say that your entity structure still makes sense, your EIN is in place, your banking path is clear or completed, your accounting system is live, your compliance deadlines are tracked, your growth risks have been reviewed and your documents are organised and accessible.

If you cannot say all of that yet, the goal for the next phase is not more activity. It is more control.

Your 90 day action checklist

Week 1 to 2

1. Save formation documents.

2. Confirm registered agent and address setup.

3. Prepare core internal documents.

4. Sense check entity and state choice.

Week 2 to 3

1. Prepare and submit EIN application.

2. Confirm all business details are consistent.

3. Organise records and confirmations.

Week 3 to 4

1. Shortlist banks.

2. Gather supporting documents.

3. Review address and verification requirements.

4. Map payment processor needs.

Month 2

1. Set up QuickBooks or Xero.

2. Create bookkeeping routines.

3. Separate business and personal activity.

4. Identify key tax and filing obligations.

Month 3

1. Build compliance calendar.

2. Review foreign ownership reporting requirements.

3. Assess sales tax and multi state exposure.

4. Check whether payroll, contractor or nexus issues are emerging.

What UK founders usually get wrong

1. They think formation means completion

It does not. Formation creates the entity. It does not finish the setup.

2. They delay accounting

That usually leads to messy records and harder filings later.

3. They underestimate banking friction

Banks can ask for more proof than founders expect, especially for non resident founders.

4. They assume inactive means no compliance

That is one of the most expensive misunderstandings in U.S. setup.

5. They ignore multi state growth until it becomes urgent

By the time it feels urgent, cleanup is usually harder.

FAQ

Is my U.S. company fully set up once formation is complete?

No. Formation gives you the legal entity, but you still need to handle EIN, banking, accounting, compliance tracking and often tax planning before the business is fully operational.

What should I do first after US company formation?

Usually the first priorities are confirming your formation documents, reviewing your address setup, applying for your EIN and preparing for banking.

Can I wait to set up bookkeeping until I start earning revenue?

You can, but it often creates unnecessary problems. It is much easier to put systems in place early than to rebuild records later.

Do I still have filing obligations if the company is inactive?

Often yes. Annual reports and returns may still be required even if the entity is not trading.

Why does the first 90 days matter so much for UK founders?

Because you are managing U.S. admin from overseas. Small setup mistakes around EINs, addresses, banking and filings can take longer and cost more to fix when you are handling everything cross border.

CTA

If you have completed your U.S. formation but are not fully confident about what comes next, Set Up Stateside can help you turn a newly formed entity into a workable, compliant business setup.

We support UK founders with entity formation and EIN support, U.S. bank account guidance, accounting setup in QuickBooks or Xero, bookkeeping and reconciliation, federal and state filing support, ongoing compliance management and multi state planning as the business grows.

Explore our services page and get in touch via our contact page