HMRC investigation support in Mansion House

Anyone in Mansion House who has received an HMRC letter: sole traders and landlords with a Self Assessment compliance check, companies with a Corporation Tax or VAT enquiry, employers facing a PAYE review, people who have received a nudge letter about offshore income, crypto or property, and those who know their past returns were wrong and want to disclose before HMRC finds out.

• Review of HMRC's letter and the return or period under check, with a frank assessment of exposure before you commit
• Agent authorisation so that HMRC deals with us directly and deadlines are managed on your behalf
• A controlled first response: what HMRC is entitled to, what it is not, and the information actually required
• Meetings and correspondence handled, with you briefed before and after every exchange
• Voluntary disclosures prepared and negotiated where tax has been underpaid, minimising penalties
• Penalty mitigation, suspension requests, statutory reviews and tribunal appeals where the facts support them

1. Tell us your situation

   A short message or call about what you do and what needs filing. We ask the questions that determine the right package and nothing more.

2. Fixed fee in writing

   You receive one price for the work, confirmed by email before anything starts. It does not change if the job takes longer than we expected.

3. Send records, review the draft

   Records come by WhatsApp or email. We prepare the draft, explain the figures in plain English and answer your questions.

4. We file, you get the receipts

   Once you approve and the fee is settled, we submit electronically and forward the HMRC or Companies House acknowledgement the same day.

Mansion House is in Central London, within City of London, in the EC4V postcode district, England. Income tax in England follows the UK rates: 20% basic to £50,270, 40% higher to £125,140 and 45% additional, with the personal allowance of £12,570 tapered away above £100,000. National Insurance, VAT and Corporation Tax are UK-wide, and Stamp Duty Land Tax applies to property purchases.

The Self Assessment calendar

The tax year runs from 6 April to 5 April. Anyone new to Self Assessment must register by 5 October after the end of the tax year in which their untaxed income began. The online return and the balancing payment are due by 31 January, with a second payment on account on 31 July where they apply. Paper returns have an earlier deadline of 31 October and are rarely sensible.

Payments on account

If your Self Assessment bill exceeds £1,000 and less than 80% of your tax was collected at source, HMRC asks for two advance payments towards the following year, each half of the current bill, due 31 January and 31 July. The first year this happens the January payment is effectively one and a half times the bill. We model it in advance and show you how to reduce the payments if income is falling.

Late filing penalties

HMRC's penalties for a late Self Assessment return are automatic: £100 the day after 31 January, £10 a day from three months late up to £900, then the greater of £300 or 5% of the tax at six and twelve months. Interest and separate late-payment penalties apply to the tax itself. Companies House charges £150 to £1,500 for late accounts, doubling for a second consecutive year.

Making Tax Digital for Income Tax

MTD for Income Tax replaces one annual return with quarterly digital updates and a year-end declaration, submitted from software. The threshold is gross trading and property income, measured two years earlier, and started at £50,000 in April 2026 before falling to £30,000 in April 2027. Anyone affected needs digital record keeping in place before their start date, not after.

The VAT registration threshold

Watching the rolling twelve-month turnover figure is one of the quiet jobs of monthly bookkeeping, because the £90,000 VAT threshold arrives silently. Crossing it brings quarterly returns, Making Tax Digital software and a decision about schemes. Crossing it late brings a bill for VAT you could not recover from customers and a penalty for failing to notify.

Corporation Tax rates and marginal relief

Companies pay Corporation Tax at 19% on profits up to £50,000 and 25% on profits over £250,000. Between those figures marginal relief applies, producing an effective rate that rises gradually and a marginal rate of 26.5% on each pound in the band. The thresholds are divided by the number of associated companies, so a director with two companies has thresholds of £25,000 and £125,000 for each.

Salary versus dividends

Directors of their own companies usually take a salary at or just above the National Insurance thresholds, which keeps the year qualifying for State Pension and is deductible for Corporation Tax, with further income as dividends. Dividends above the £500 allowance are taxed at 10.75%, 35.75% and 39.35% by band and can only be paid from distributable profits after tax, with a minute and voucher each time.