The Round Treasury Complete Guide to Bank Accounts

Published 11 September 2024. Updated 28 July 2026.

The right business bank account structure for a UK startup depends on its stage: pre-seed and seed founders typically need just two accounts (current plus savings) across one or two banks, growth-stage companies typically run three to five accounts across two to three banks, and mature companies typically run five or more accounts across three or more banking institutions. The priority shifts from "never miss payroll" early on to "optimise yield and manage risk" later.

TL;DR

• Early stage (pre-seed/seed, up to £10M revenue): 2 accounts, 1 to 2 banks. A current account for daily operations plus a savings/treasury account for reserves.

• Growth stage (Series A-C, £10M to £75M revenue): 3 to 5 accounts, 2 to 3 banks. Add high-interest savings, foreign currency accounts, and specialised accounts as needed.
• Maturity stage (Series D to public, £100M+ revenue): 5+ accounts, 3+ banks. Full treasury management policy, multiple FX accounts, investment portfolios.
• The two biggest mistakes: mixing personal and business funds (a due-diligence and audit headache), and over-optimising for yield with aggressive sweep accounts at the expense of payment liquidity.
• FSCS deposit protection is £120,000 per eligible depositor, per banking institution (effective 1 December 2025, up from £85,000), which is the practical ceiling to keep in mind when deciding how many banks to spread cash across at any stage.

What Bank Accounts Does an Early-Stage Startup Need?

At pre-seed and seed (up to £10M revenue, up to 75 employees), the founder is usually the one managing cash directly: there isn't enough day-to-day financial activity yet to justify a dedicated finance hire. The structure that works is deliberately simple: two accounts across one or two banking institutions.

• Current account: covers daily expenses, payroll, and customer payments. Keep roughly 2 to 3 months of operating expenses here, not more; excess cash sitting idle in a non-interest current account is a missed opportunity.
• [Savings/treasury account](https://www.roundtreasury.com/solution/treasury): the safety net. Excess cash beyond the 2 to 3 months of operating expenses goes here, ideally in an interest-bearing savings account or money market fund rather than sitting flat.

Priorities at this stage, in order: never miss payroll, keep the banking structure simple, manage receivables and payables on time, and mind FX fees if you're paying or getting paid in a currency other than your operating currency. Interest earned at this stage is a bonus, not the job: the job is building the company.

What Bank Accounts Does a Growth-Stage Startup Need?

Between Series A and C (£10M to £75M revenue, 75 to 500 employees), the first dedicated finance hire typically appears, ranging from a part-time bookkeeper to a VP of Finance or CFO. Account structure expands to 3 to 5 accounts across 2 to 3 banking institutions:

1. [High-interest savings or money market accounts](https://www.roundtreasury.com/features/get-coverage-for-your-treasury-funds): move surplus funds here rather than letting them sit idle in a current account.
2. Foreign currency accounts: essential once you have full-time employees or major costs outside the UK, so international payroll and vendor payments aren't exposed to unnecessary FX risk.
3. Specialised accounts (escrow, trust, or investment accounts): used for specific transactions rather than day-to-day operations.

This is also the stage where segregation of duties starts to matter for its own sake, not just as good practice: by Series C, the person who sets up a wire transfer generally shouldn't be the same person who approves it. Once a company has roughly 18 months of runway banked, it's reasonable to start considering higher-yield investments with calculated risk.

What Bank Accounts Does a Mature Company Need?

From Series D through to public markets (£100M+ revenue or 500+ employees), a dedicated treasurer typically owns cash management, and the structure grows to 5 or more accounts across 3 or more banking institutions:

1. Multiple current/savings accounts across multiple institutions: segregated by purpose (payroll, taxes, operating expenses) and diversified to reduce concentration risk.
2. Investment accounts or corporate investment portfolios: appropriate once cash runway is significant enough to support more complex strategies.
3. Multiple FX accounts: for efficient handling of international transactions.
4. Retirement accounts for employees: increasingly a talent-retention necessity, not just a nice-to-have.
5. Escrow accounts: for large transactions, particularly M&A.

At this stage, visibility becomes the binding constraint: a treasurer needs a single, reliable view of the company's total cash position across every entity and institution, since manually checking multiple bank portals doesn't scale past a handful of accounts. A documented treasury management policy, and readiness for potential M&A due diligence, both matter more here than at any earlier stage.

Comparing Bank Account Structures by Startup Stage

What Are the Biggest Bank Account Mistakes Startups Make?

Mixing personal and business funds. This usually happens when a startup rushes to open a business account right after closing a funding round, and in the meantime routes an investor wire or early expenses through a personal account. It creates real problems later: delays getting investor wires approved, complications during M&A due diligence, and, reliably, a stern conversation with auditors. The fix is straightforward: open the business account and get KYC done before you need to receive investor funds, not after.

Overcomplicating with sweep accounts. A sweep account automatically moves surplus cash from a current account into a higher-yield vehicle (commonly a money market fund) at the end of each day, once a minimum balance is maintained. The risk is being too aggressive with the sweep threshold: if the rule prioritises maximising interest over keeping enough liquidity for large or unexpected payments, a startup can end up short on the current account exactly when it needs to make a payment. Sweep account fees can also outweigh the interest benefit in a low-rate environment, so it's worth checking the effective rate, not just the headline rate, before assuming a sweep arrangement is a clear win. The practical rule: the moment you're worried whether there's enough in the current account to cover a payment, the sweep threshold is set wrong.

What Changed in 2026

FSCS deposit protection rose from £85,000 to £120,000 per eligible depositor, per banking institution, effective 1 December 2025. That changes the practical math behind "how many banks should I spread cash across at each stage": a company can now hold £120,000 per institution before needing to diversify further for protection purposes, up from £85,000 previously. It doesn't change the underlying account-structure guidance in this piece, but it's worth updating any internal treasury policy that still references the old figure. See our full breakdown in How FSCS Insurance Can Safeguard Your Startup's Cash.