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Where annual payments, non-exempt dividends from overseas companies and income received net of Income Tax go on the CT600 - boxes 175, 180 and 185 in Tax Optimiser, with a worked example.

What every box on the CT600 Company Tax Return means, how Tax Optimiser fills it, and where the figure comes from - with an entry for each box on the 2026 form.

How non-trading gains and losses on intangible fixed assets and capital allowances against non-trade income reach the CT600 - boxes 195, 265, 290 and 830 on the Intangibles & Other Reliefs section.

When a company's accounts cover more than 12 months, Tax Optimiser keeps one set of statutory accounts but splits the Corporation Tax into two CT600 returns - the first 12 months and the remainder. How the split is decided, how profits, capital allowances and losses are divided, and how both returns are filed.

What belongs in CT600 box 205, how the Non Trade Income grid takes the income out of the trading profit and taxes it on its own line, and what each column does.

Interest on borrowing that is not for the trade - shares, let property, investments - is a non-trading loan relationship debit. How to move it out of the trade with the Non Trade Debit grid, and how a non-trading deficit is relieved in boxes 795, 260 and 263.

Find your way around the View Accounts screen: the live preview, page links and the editing actions.

Two versions of one set of accounts: what filleting removes, where each version is filed, and how amended filings work.

The Company Information, Dates, Pages and Addresses windows - the descriptive details that appear throughout the document.

Manage the directors list, sync it from Companies House, and designate who signs the balance sheet.

The four FRS 105 notes explained, including the mandatory average-employees figure and how note templates work.

How the note set grows under FRS 102 Section 1A, which notes fill themselves from the trial balance, and the accounting policies window.

Clear the validation list, record who signed and when, and keep the signed copy on file - then you are ready to submit.

How FRS 105 (micro-entity) and FRS 102 Section 1A (small company) accounts differ, and the size thresholds - including the higher limits from 6 April 2025 - that decide which one your company uses.

The Economic Crime and Corporate Transparency Act changes to accounts filing, now due on 1 April 2028, and what to check before then.

The six-character code Companies House needs to accept your filing: where it comes from and where it goes in Tax Optimiser.

What counts as dormant for Companies House, what dormant accounts contain, and how to file them with the Dormant Accounts Wizard.

Who can skip an audit, when shareholders can insist on one, and the statement the directors must sign.

The automatic penalty for filing accounts late: the bands, the doubling rule, extensions and appeals.

When your accounts are due at Companies House, how the accounting reference date sets the deadline, and what happens when you change it.

How a company is taxed on the sale of property, shares and other capital assets - recording disposals on the Chargeable Gains tab, using capital losses, and what goes in CT600 boxes 210, 215, 220 and 825.

How a company gets credit for foreign tax on its overseas income - adding sources on the Double Taxation Relief tab, how the credit is limited to the UK tax on each source, and what goes in CT600 boxes 450, 470 and 475.

How a company carries a trading loss back against earlier profits - the 12-month carry-back, three-year terminal loss relief when the trade stops, the Carry back to earlier periods panel, amending earlier returns, and CT600 boxes 45, 275, 280 and 780.

The 100% first-year allowance for new electric vans and other zero-emission goods vehicles - who could claim it, its end for companies on 31 March 2025, how to record the vehicle in Tax Optimiser, and what goes in CT600 boxes 723, 748 and 760.

How a company with investment business deducts its management expenses and the capital allowances on its investment-business assets - the Management Expenses tab, excess carried forward, and CT600 boxes 245, 255, 850 and 733.

Interest a company receives is a non-trading loan relationship credit, taxed in CT600 box 170 after netting against interest paid. When Tax Optimiser picks it up for you, when it does not, and how to fill in the Non Trade Credit grid.

Mark rental income and letting costs as UK property in the P & L, and Tax Optimiser reports the property business in boxes 190, 805 and 250 - separately from the trade.

Enable the service, link Companies House, add your UTR and create your first accounting period.

Import from Xero, QuickBooks or a spreadsheet, or key the trial balance by hand - then make sure it balances.

Work through the calculation sections - disallowables, adjustments, donations and non-trade income - and watch the payable figure update live.

Disallow depreciation, record your asset additions, and claim the Annual Investment Allowance.

Read the loss movement, record brought-forward and carried-back losses (pre- and post-2017), and let the carried-forward balance calculate itself.

Read the cross-referenced computation, finish the statutory accounts, and clear the validation checks.

Sign the accounts, clear the pre-flight checks, and file to HMRC and Companies House through the guided wizards.

The R&D supplementary page of the Company Tax Return: who has to file one, how the seven RDEC steps turn a claim into cash, and what every box from L5 to L210 means.

The controlled foreign company charge, the foreign branch exemption election and hybrid mismatch disclosures - how to complete the CT600B in Tax Optimiser and what every box from B1 to B85 means.

AVEC, VGEC and the creative reliefs - how an expenditure credit becomes a payable credit, how to claim it in Tax Optimiser and what every box on the CT600P means.

How a company gets money back from its Company Tax Return - R&D and creative credits paid in cash, Income Tax repaid, bank details - and what every CT600 repayment box from 860 to 970 means.

Directors' loans, the 33.75% section 455 charge and the relief that cancels it - how to enter loans in Tax Optimiser and what every box on the CT600A means.

A Community Interest Company files the same CT600 and accounts as any company. The difference is the CIC34 report it sends to Companies House each year - here is how to prepare it in Tax Optimiser.

A members' club or association files a CT600 but nothing at Companies House, and its members' income is not taxable. Here is the whole journey, from signing up to sending the return.

Replace a set of accounts you've already filed: check the original went through, correct the figures, mark them as amended, fill in the revision detail Companies House requires, and re-file.

A CIO files a CT600 but nothing at Companies House, and its SORP accounts go to HMRC as a PDF. Here is the whole journey, from signing up to sending the return.

Set the organisation's Corporation Tax company type to Charity or CASC and the CT600E supplementary page appears, ready to complete and file with the CT600.

What Making Tax Digital for Income Tax is, the four-step setup on your dashboard, and the difference between demo mode and live mode.

Where your personal details go, and why your National Insurance Number is required before any submission.

How to authorise Tax Optimiser to talk to HMRC, the difference between an individual and an agent connection, and when to reconnect.

How Tax Optimiser retrieves your income sources from HMRC, the three business types, and what each business holds.

The per-business settings that shape how figures are reported: cash or accruals accounting, standard or calendar quarters, and full or consolidated expenses.

How quarterly figures get into Tax Optimiser: uploading a spreadsheet, the full and consolidated example templates, and mapping your own cells.

Sending a quarterly update: reading the values, confirming the declaration, and amending a quarter after it has gone.

The end-of-year additions - dividends, foreign income, pensions, reliefs - that complete the year before your tax is worked out.

Asking HMRC to work out the tax on what you have reported, the three kinds of calculation, and how to read the result.

The once-a-year declaration that crystallises your tax bill, what must be done first, and how to re-open a year to amend it.

Prepare and file SA800 Partnership Tax Returns for LLP and partnership clients: a six-step wizard, self-calculating boxes, the official form as a PDF, and direct HMRC filing.

Where the LLP (SA800) menu appears, what the returns list shows, and what New Partnership Period prefills for you.

The Details step: partnership name and live-checked UTR, boxes 3.1/3.2, period dates, the agent and amended-return declarations, and the page 2 questions.

The full SA800 income and expenses page: entering income and expense totals, capital allowances, and how the calculated boxes 3.65 and 3.73 drive the rest of the return.

Boxes 3.99 to 3.115: assets, liabilities and the partners' accounts, with all three totals calculated and a built-in way to check the sheet balances.

Adding partners, boxes 6-12, entering each partner's share, and the live checks: the allocation-vs-return warning and the UTR check that prevents error 8205.

Land & Property, Foreign, Chargeable Assets and Savings on one screen - each page files only when it carries figures, and SA801's net position calculates itself.

The review summary and its two warnings, printing the official SA800 form, what Submit really does (sign, send, poll), and handling rejections and amendments.

Prepare and file full SA100 Self Assessment returns for clients not in MTD — with a live tax calculation — from inside Tax Optimiser. Beta access via support@taxoptimiser.co.uk.

Opening a client's first Self Assessment year, the pre-filled personal details, choosing the return's pages with Add Section, and the save-as-you-go model.

Entering the return's income pages: multiple employments, self-employment short and full pages, UK property, and interest and dividends — with the HMRC box references on every field.

Pension contributions, Gift Aid, Marriage Allowance, the High Income Child Benefit Charge, student loan plans, and the return's closing boxes.

The live SA302-style calculation: the staged statement, the band-by-band breakdown, PAYE coding adjustments and the claim to reduce payments on account, warnings, and the downloadable SA302 PDF.

Filing a prepared return: the five pre-flight checks, the declaration, what happens during submission, and reading the submission history.

Accepted years lock; Reopen for amendment files a replacement return. The amendment deadline, rejections, and chasing stuck submissions.

Partnership shares, foreign income with FTCR, trust and estate income, capital gains, residence status and the SA101 pages — how each supplementary schedule is entered and calculated.

Generate a Sodium API key, paste it into your firm settings, pick your practice, and sync your limited-company clients into Tax Optimiser in one click.

Every set of accounts and every CT600 hangs off an accounting period. Here is how the system creates them for you automatically from Companies House, and how to add one by hand when you need to.

Every set of accounts and every CT600 hangs off an accounting period. Here is how the system creates them for you automatically from Companies House, and how to add one by hand when you need to.

The map of the journey: set your firm's filing credentials once, then create each client and file accounts and Corporation Tax through the two wizards.

Where the firm's Presenter ID and Government Gateway login live, what each one is, and how to obtain a Presenter ID.

Two ways to add a client: search the live Companies House register, or create by name and fill the company number in yourself.

The Gateway login is firm-wide with a per-client override; the Presenter ID is firm-only for firm-managed clients. Here are the rules, the override, and the errors.

Filing a client's accounts as a firm: credits instead of per-period fees, the firm's presenter credentials, and the pre-flight checks before the wizard sends.

Filing the CT600 for a client: the UTR and Gateway login it needs, what the warnings mean, and the final confirmations before sending.

Every period follows the same three stages before you can file: get the trial balance in, build and review the accounts, and build the Corporation Tax computation. Here's the map.

Bring a year's figures in from Xero, Sage 50 or any spreadsheet, map them to HMRC and Companies House-ready accounts with AI help, and make it balance.

Renew your HMRC connection in two minutes, and sort out the "incorrect Government Gateway account" message.

Switch on the VAT service, enter your VAT registration number and find your way around.

Tell Tax Optimiser which sheet and cells of your spreadsheet hold the nine VAT-return boxes.

Practise the HMRC connection in demo mode, then grant authority for real and let your periods flow in.

Drag your spreadsheet onto the open period and check the nine boxes it fills.

Accept the declaration, get HMRC's acceptance back and keep the receipt as proof of filing.

Track what HMRC says you owe and have paid, and settle into the quarterly routine.

Learn how to enter your firm's Companies House Presenter ID and Auth in TaxOptimiser, and how to apply for credentials if you don't yet have them.