Corporation tax returns in Mona

Limited companies in Mona of every size below the large-company regime: companies whose accounts are prepared by another firm or in-house and need the tax return filed, companies with capital expenditure to claim, companies that have made a loss and want it used well, groups of associated companies, and companies whose CT600 is already overdue.

• Corporation Tax computation reconciling accounting profit to taxable profit, with every adjustment explained
• Capital allowances claimed in full: annual investment allowance, full expensing, writing-down allowances and the special rate pool
• Loss relief planned and claimed: carry back, carry forward and group relief where it applies
• Marginal relief and associated-company rules applied correctly between the 19% and 25% rates
• CT600 with supplementary pages, iXBRL-tagged accounts and computation, filed electronically with HMRC
• Payment note with amount, due date and HMRC reference, and reminders before the payment and filing dates

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.

Mona is in Wales, Wales. Welsh taxpayers pay Welsh rates of income tax, set by the Senedd and currently matching the English bands, collected under a C-prefixed tax code. National Insurance, VAT and Corporation Tax are UK-wide. Property purchases in Wales pay Land Transaction Tax to the Welsh Revenue Authority rather than Stamp Duty, with its own bands and rates.

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

Lateness is expensive in a way that compounds. For individuals, £100 immediately, then daily penalties, then percentage-based ones at six and twelve months, with interest running on unpaid tax throughout. For companies, Companies House penalties scale with delay and double on repeat, and HMRC adds its own for a late CT600. Filing on time is the cheapest tax planning there is.

Making Tax Digital for Income Tax

Making Tax Digital for Income Tax began in April 2026 for sole traders and landlords with qualifying income over £50,000, extends to those over £30,000 in April 2027 and is planned for £20,000 in April 2028. It requires digital records in compatible software and four quarterly updates to HMRC each year, with a final declaration replacing the traditional return. Payment dates are unchanged.

The VAT registration threshold

VAT registration is compulsory once taxable turnover in any rolling twelve-month period exceeds £90,000, or when you expect to exceed that in the next thirty days alone. The test is rolling, not by tax year, and includes zero-rated sales. Businesses regularly cross it without noticing, and late registration means accounting for VAT on sales where it was never charged to customers.

Corporation Tax rates and marginal relief

Since April 2023 there have been two Corporation Tax rates, 19% small profits and 25% main, with marginal relief smoothing the transition between £50,000 and £250,000 of profit. The band is where planning matters: each pound of profit in it is taxed at an effective 26.5%, so pension contributions and capital expenditure timed to keep profit below £50,000 are worth more than they look.

Salary versus dividends

The salary-and-dividend split is the central planning decision for an owner-managed company. Salary costs employer National Insurance above £5,000 but is deductible; dividends are not deductible but attract lower personal rates and no National Insurance. The optimum changes each April with the thresholds and depends on the director's other income, so it should be set deliberately every year.