US UK Tax Returns Preparation: What an American Living in London Should Expect on Fees and Timeline

US UK tax returns preparation rarely costs what people expect, and it rarely takes as long as they fear either. Most Americans in London budget for one number and get quoted another, then panic about a deadline that’s still months away. Neither reaction is warranted once you understand what actually drives price and how the calendar really breaks down.

This guide walks through both in detail — the real cost drivers, typical ranges, a full week-by-week timeline, and the practical steps that keep your fee as low as it reasonably can be — so you can plan your year rather than scramble through it.

What US UK Tax Returns Preparation Actually Covers

A US federal return sits at the center, but that’s rarely the whole job. Most Americans in London also need a UK Self Assessment return, an FBAR for any foreign accounts over the $10,000 threshold, and often Form 8938 alongside it. Add a workplace pension, a rental flat, or a small side business, and the return grows again. US/UK tax return preparation for a straightforward employee looks nothing like the version for a founder with equity or a landlord with two properties — and the fee reflects that difference.

It helps to think of the engagement as several linked projects rather than one form. The US federal return itself might include a Foreign Earned Income Exclusion or Foreign Tax Credit calculation, state tax considerations if you still have US-source income or ties to a particular state, and any investment income reporting. The UK Self Assessment return covers employment income beyond what’s taxed through PAYE, any self-employment, property income, and capital gains. On top of that, the FBAR and Form 8938 are separate disclosures with their own thresholds and deadlines. Each layer adds time, and time is what you’re actually paying for.

What Drives the Cost

Four factors move the price more than anything else. Income complexity comes first: salary and interest cost less to process than stock options, PFICs, or partnership income. Foreign accounts come second — each additional account adds line items to the FBAR and Form 8938, not a huge amount individually, but it accumulates. Filing history matters too. A current, on-time filer pays a routine fee; someone catching up several years of missed returns pays for a materially larger project. Finally, coordination between US and UK filings takes real time. Foreign tax credits have to be calculated correctly so the same income isn’t taxed twice, and that reconciliation work is where much of the fee actually goes.

A fifth factor matters more than people expect: how organized your records are when you hand them over. A client who arrives with a single spreadsheet listing every account, every P60, and every dividend statement in date order costs meaningfully less to serve than one who hands over a folder of unsorted PDFs and asks the preparer to work out what’s missing. Preparation time isn’t just about the complexity of your tax position — it’s also about how much of the sorting has already been done before the engagement starts.

Typical Fee Ranges in London

Expect a straightforward US federal return with FBAR to sit at the lower end of the market, rising as schedules, foreign accounts, or self-employment income get added. A combined US and UK engagement — federal return, Self Assessment, and FBAR handled by one coordinated team — typically costs more than doing them separately with two unconnected firms, but it usually costs less than the two firms’ fees added together, because the preparer isn’t duplicating the fact-finding. Multi-year catch-up work under the IRS streamlined procedures costs more again, simply because it covers several years of returns rather than one.

Company ownership changes the picture further. If you own 10% or more of a UK limited company, a Form 5471 is generally added to the engagement, and this is one of the more time-intensive schedules in the entire US return — it requires the company’s statutory accounts, share register, and details of any dividends or loans, cross-referenced against your personal filing. Expect this to add a noticeable premium to the base fee, proportional to how many entities and years are involved.

Treat any quote that arrives without a single question about your income sources with suspicion. A fair quote follows a short conversation about your accounts, employment, and property — not a flat rate pulled from a price list. If two quotes for what feels like the same situation differ significantly, ask each firm to itemize exactly what’s included, since the underlying scope is often not actually identical.

Fixed Fee Versus Hourly Billing

Most reputable cross-border firms quote a fixed fee once they understand your situation, rather than billing hourly. Fixed fees give you cost certainty before any work begins, which matters when the scope of a return can shift as documents come in. Hourly billing can work well for genuinely unpredictable engagements — an in-progress IRS inquiry, for example — but for annual compliance work, a fixed quote confirmed in an engagement letter is the safer structure for both sides. If a firm insists on open-ended hourly billing for a routine annual return, ask why, since it’s worth understanding before you commit.

Two Client Profiles, in Practice

It helps to see how these factors actually combine. Consider two Americans living in London with very different fee outcomes.

The first is a salaried employee on a single PAYE income, with one UK current account, one UK savings account holding under $10,000, and no US-source income beyond bank interest. This is close to the simplest version of US/UK tax return preparation, and the fee reflects a routine engagement: gather a handful of documents, prepare two returns, confirm foreign tax credit treatment on straightforward employment income, and file.

The second is a startup employee with equity compensation, a UK workplace pension, two UK investment accounts, a small freelance consulting sideline, and 12% ownership in a UK limited company she co-founded with two colleagues. Her engagement involves stock option reporting, PFIC analysis on the investment accounts, self-employment income reconciliation across both countries, and a full Form 5471 for the company. The fee for her return sits well above the first example — not because the firm is charging more for the same work, but because the actual volume and complexity of work is genuinely several times greater.

How Long Does It Take?

A clean, current-year return with organized documents can be finished in two to three weeks once your accountant has everything they need. Add complexity — foreign investments, self-employment, a first-year move between countries — and four to six weeks becomes realistic. Catch-up filings under the streamlined procedures often run eight to twelve weeks, because several years of records need collecting and cross-checking before anything gets submitted.

Seasonality also plays a role that’s easy to underestimate. January is the busiest month for UK-focused work because of the HMRC deadline, and March through mid-April is the busiest period for US-focused work. Engaging a preparer in either peak window generally means a longer queue before work even starts, regardless of how simple your return actually is. Engaging in the quieter months — autumn for UK work, or January and February for US work — usually means faster turnaround purely because of capacity.

The Week-by-Week Reality

• Week 1 — Onboarding call, engagement letter, and a document checklist tailored to your situation.
• Weeks 1–2 — You gather P60S, W-2s, bank interest statements, and pension or investment summaries.
• Weeks 2–3 — Your accountant drafts the US federal return and the UK Self Assessment in parallel, checking how foreign tax credits interact between the two.
• Week 3–4 — You review the draft, ask questions, and confirm figures before anything gets filed.
• Week 4+ — Your accountant files both returns and confirms submission with HMRC and the IRS.

Two dates anchor this whole process. The IRS deadline sits at April 15, though Americans abroad automatically receive an extension to June 15, and a further extension to October 15 is available on request. HMRC’s online Self Assessment deadline falls on January 31 following the end of the UK tax year, with an automatic £100 penalty for missing it — see GOV. UK’s penalty guidance for the full escalation schedule. Because the two calendars don’t align, most experienced preparers start UK work in the autumn and US work in the new year, so nothing gets rushed at either deadline.

What Happens If You Need to Amend Afterward

Occasionally a document arrives after filing — a corrected dividend statement, a late-issued tax certificate — that requires an amendment. This isn’t unusual and isn’t typically expensive to fix if caught early, but it’s worth asking upfront whether amendment support is included in your engagement or billed separately. A firm that flags this possibility proactively, rather than treating it as a surprise add-on later, is generally the more transparent choice.

Currency and Exchange Rate Considerations

US returns require UK-earned income to be converted to US dollars, and the IRS accepts either the annual average exchange rate or actual transaction-date rates, depending on the type of income involved. This sounds like a minor technical detail, but it can meaningfully affect your reported figures, particularly in a year with significant currency movement between sterling and the dollar. A preparer experienced in cross-border returns handles this consistently across every line item; an inconsistent approach here is a subtle but real source of errors in DIY or inexperienced preparation.

How to Avoid Paying More Than You Should

Start early. A return begun in November costs the same in professional time as one begun in January, but the January version often attracts a rush fee once deadlines tighten. Keep a running folder of P60S, interest certificates, and account statements through the year rather than hunting for them in a panic. And ask your preparer directly what’s included in the quoted fee — FBAR, Form 8938, and correspondence with HMRC or the IRS sometimes sit outside the base price, and you want that clear before you sign anything.

It’s also worth asking whether the fee is likely to change materially year over year, assuming your situation stays roughly the same. A firm that can answer this confidently understands your file well; one that hedges every year suggests less continuity in how your return is actually handled.

Getting Started

Jungle Tax handles US and UK tax return preparation for Americans across London through a single coordinated engagement, covering the US Tax Services for Individuals side and the UK Tax Services for Individuals side under one team, so foreign tax credits get calculated correctly the first time. If your situation involves cross-border investments or a business interest, the Cross-Border Tax Planning service covers that layer too. A short call is usually enough to scope the work and give you a real number, not a guess.

The fastest way to get a real quote is through the contact page, where a short outline of your situation is enough to get the conversation started.

Contact Us

Jungle Tax is a specialist US and UK cross-border accountancy firm, and the team is happy to talk through your specific situation before you commit to anything.

Email: hello@jungletax.co.uk

Phone: 0333 880 7974

London Office: Waverley House, 9 Noel St, London W1F 8GQ

Website: jungletax.co.uk/contact