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SA100 · 2025/26 · deadline 31 Jan 2027Live — Available now

Your Self Assessment, drafted while you sleep.

ac-co reads your bank, your accounts, your broker and HMRC's own pre-population — then fills every box of your SA100 and supplementary pages, builds the tax computation, checks it line by line, and files it. You review once and tap submit.

£29 simple / £65 complete per return (was £59 / £129) · 50% off until 14 January 2027 · No card · UK-only · HMRC-recognised
BUILT FORSole tradersLandlordsInvestors & cryptoHigh earnersSide hustles
Live · click to watch
Wired into
HMRC · pre-pop + filingOpen Banking · every UK bankXero · booksQuickBooks · booksYour broker · dividends
HOW IT WORKS

From connected to filed, in four moves.

01

Connect

Open Banking, your accounting tool, your broker and HMRC's pre-population — linked in two minutes, read-only.

02

Draft

ac-co fills every box of the SA100 and each supplementary page, tagging every figure with the source it came from.

03

Check

Line-by-line reconciliation against HMRC's records, last year's return and your documents. Anomalies flagged before you see them.

04

File

Review the computation on your phone, tap submit. Direct to HMRC, receipt and IRmark stored for six years.

WHAT YOU GET

Everything this plan files, keeps and tells you.

We cover

  • SA103SSelf-employment (short)
  • SA103FSelf-employment (full)
  • SA105UK property
  • SA106Foreign income
  • SA108Capital gains
  • SA109Residence & domicile

Files for you

Sent to HMRC, with a receipt you keep.

  • SA100 with an HMRC receiptEvery box approved by you before it's submitted.

Keeps for you

The workings stay with the return, figure by figure.

  • Your SA302 calculation
  • The document behind every figure

Tells you

See the figure for free; pay only when you file.

  • Your refund or bill — before you pay us anything

See your figure for free. Pay when you file.

HMRC's own form is free but unaided; an accountant checks your work but makes you wait for it.

RowHMRC onlineAn accountantac-co
£/returnFree£150–£400 [Sleek — accountant fees for Self Assessment, UK, 2026-09-13]£29–£65
TurnaroundAs long as it takes youAround two weeks, appointment-dependentMinutes, once your documents are in
See the draft before you payYou see it as you typeNoYes
You approve every box before it's submittedYesThey submit for youYes

Accountant fee dated 2026-09-13 — check their own quote.

PRICE PER RETURN

Pay per return. Nothing monthly.

Draft for free, pay when you file. Two tiers, decided by how many supplementary pages your return needs.

Launch offer · 50% off until 14 January 2027
Simple
PAYE + one extra income
£29£59/ return

For one supplementary page — a side hustle, some dividends, or a single rental.

Start a return — £29
  • SA100 + one supplementary page
  • HMRC pre-pop reconciled
  • Full tax computation
  • File direct to HMRC
  • Receipt stored 6 years
Complete
Most self-employed & landlords
Most picked
£65£129/ return

Every income type, every supplementary page, capital gains and reliefs — drafted and filed.

Start a return — £65
  • Everything in Simple, plus:
  • Unlimited supplementary pages
  • Capital gains (SA108) — shares & crypto
  • Section 24 + pension optimiser
  • Payments-on-account planning
  • Priority human review add-on

No card to start — you pay at the filing step. Filing every year, with books and VAT on the same numbers? See the monthly plans →

No sign-up — try it right here

Try the calculator — no sign-up.

Quick take-home pay

PAYE · 2026/27 · England, Wales & NI

Net take-home

£28,720/ year

≈ £2,393 / month

Income tax

£4,486

Employee NI

£1,794

See full breakdown

Estimate only, based on what you enter here — not a substitute for your full tax computation. All calculators →

OBJECTIONS

Before you buy.

What if it's wrong?

Every figure traces to a source document or bank transaction, and nothing submits itself — you review the full computation and approve before it's sent to HMRC.

Will I see every box before it's submitted?

Yes. The draft shows every box on every page you need, exactly as HMRC will receive it, with the source behind each figure alongside it.

Is this actually recognised by HMRC?

Yes — ac-co is HMRC-recognised software for Self Assessment, filing through the official API. See HMRC's own list of recognised suppliers, linked above.

I've left it to 30 January.

The draft still builds from your bank and documents in minutes, not days. Start now and you can still review and file before the 31 January deadline.

I already have an accountant.

Invite them into the same draft to review before you file — or use ac-co for the parts they don't need to see, like the running SA302 estimate.

FILE THIS YEAR'S RETURN

Stop dreading January. Let it draft itself.

UK Self Assessment · 2025/26 · HMRC-recognised · pay only when you file.

▸ Individual sign in
31 Jan 2027 deadline · most beta returns filed in under 10 minutes
GUIDES

Everything else you need to know.

Self Assessment Deadline 2025/26: Every Date You Need to Know

The full Self Assessment calendar for the 2025/26 tax year — registration, paper and online filing, and both payment dates, each sourced to gov.uk.

Self Assessment Late Filing Penalty: The Full Scale

What HMRC charges for a late Self Assessment return or payment, what counts as a reasonable excuse, and how to appeal — every figure linked to gov.uk.

How to Get Your SA302 from HMRC

What an SA302 is, why mortgage lenders ask for one, and the two ways to get yours from HMRC: through your personal tax account or your filing software.

How to Find Your UTR Number

What a UTR is, where to find one you've already got, how long a new one takes to arrive, and what to do if HMRC hasn't sent you one at all.

Sole traders

Turnover and allowable expenses from your books or bank feed, plus the £1,000 trading allowance.

Landlords

SA105 boxes, the Section 24 finance-cost reducer and the property allowance, matched per tenancy.

CIS subcontractors

Reclaim CIS tax deducted at source — SA103 boxes matched to your payment and deduction statements.

File from ChatGPT or Claude

Prepare and file your SA100 straight from the AI assistant you already use.