A Corporation Tax Accountant for Your UK Startup

By Shaun Azam - ICAEW chartered accountant, ex-PwC, built a venture-backed startup that raised over $15m before training as an accountant

If you've just registered a UK limited company, or you're a few months into trading with a corporation tax deadline starting to loom, here's the plain answer: what a corporation tax accountant does for a startup specifically, when to bring one in, what to check before you pay for one, and how startup reliefs like R&D fit into the return.

Corporation tax calculated and filed - without you learning what a CT600 is

The core job is straightforward: work out the company's taxable profit after adjusting for disallowable expenses and capital allowances, apply any reliefs it qualifies for, then prepare and file the CT600 with HMRC and tell you what's actually owed.

For a startup, that job has a few extra wrinkles a generalist practice sometimes misses. A first accounting period longer than 12 months has to be split into two separate CT600s, because HMRC won't accept one return covering more than a year. Losses need recording properly so they carry forward and reduce the bill once the company turns a profit. And the company's HMRC record has to be set up correctly from incorporation, not patched together after the fact.

Get one in before your first accounting period ends - not after HMRC's letter arrives

Most founders only start thinking about corporation tax when the first set of accounts is due, or when a letter from HMRC turns up. By then the accounting period is already fixed, expenses have gone through without the paperwork that would have made them deductible, and the director's loan account is already a mess to untangle.

The useful moment to bring an accountant in is at incorporation, or as soon as the company starts trading, because HMRC needs to be told within 3 months of trading starting. Most of what actually saves money, how you take money out of the company, what counts as a deductible cost, whether R&D relief applies, is far easier to set up right from day one than to fix after a year of guessing.

One flat fee covers the return and the advice - so a phone call never turns into an invoice

A lot of small practices price the year-end corporation tax return cheaply, then bill separately for everything around it: a call about a director's loan, an email answering an HMRC letter, advice on a purchase before you make it. The return itself is rarely the expensive part.

Before you sign up with anyone, ask what's included for the fee you're quoted. Does it cover them dealing with HMRC directly on your behalf, or does that get billed as extra work? Is advice on salary versus dividends part of the service, or an add-on you'll be quoted for later? At Absolv all of that sits inside one flat monthly fee, and we file directly with HMRC and Companies House on your behalf.

R&D and startup reliefs checked every year - not missed because nobody asked

Startups are more likely than the average small company to qualify for reliefs a generalist accountant won't always think to raise: R&D tax relief if you're building something technical, capital allowances on equipment you've bought, loss relief if you're pre-revenue and spending more than you're bringing in.

None of these apply automatically. Each one has to be identified, evidenced properly, and claimed correctly on the return the first time, because amending a CT600 after the fact to add a relief you missed is a lot more work than getting it right at filing.

Frequently asked questions