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SA100 · 2025/26 · deadline 31 Jan 2027

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.

See the income types
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 · dividendsCrypto exchanges · crypto gains
0
supplementary pages supported
SA102 · 103 · 105 · 106 · 108 + more
0%
of HMRC pre-pop pulled in
PAYE, interest, pensions — reconciled
0 min
median time from connect to submit
measured across private beta
£0
median extra relief found
allowances most people miss
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.

EVERY INCOME TYPE

One return for every kind of money you make.

Salary, self-employment, rent, dividends, interest, crypto, capital gains, foreign income — ac-co knows which supplementary page each belongs on, and routes every transaction to the right box automatically.

  • Self-employmentTurnover and expenses straight from your books or bank. Cash-basis or accruals, simplified or full.
  • Property (SA105)Rent matched per tenancy; Section 24 finance-cost reducer applied. Cross-imports from ac-co.landlord.
  • Dividends & interestPulled from your broker and reconciled to HMRC's pre-pop. Allowances applied in the right order.
  • Capital gains (SA108)Share and crypto disposals matched, pooled (s.104) and gain-calculated. Annual exempt amount netted off.
SA100 · 2025/26
Drafting from live data
HMRC connected
SA102.1Pay from this employment£18,600
SA102.2UK tax taken off (PAYE)−£2,940
SA103.15Turnover — design studio£64,200
SA103.31Total allowable expenses−£21,450
SA105.20Rental income — one flat£14,400
+ 7 more boxes · 5 pages
reconciling…
TAX COMPUTATION

The maths, shown in full — and never wrong.

ac-co builds the SA302-style computation in front of you: every band, every allowance, the dividend and savings nil-rates, the Section 24 reducer, payments on account and student loan — in the order HMRC applies them.

  • Bands & allowancesPersonal allowance taper, basic/higher/additional bands, starting-rate-for-savings — all handled.
  • Reliefs in orderPension relief, Gift Aid band extension, Marriage Allowance, finance-cost reducer applied correctly.
  • Payments on accountCalculated and scheduled, with the July balancing payment forecast so there are no surprises.
  • Always reconciledEvery figure traces to a source. The number you submit is the number you can defend.
SA100 computation
Total income£83,010
less Personal allowance−£12,570
Taxable income£70,440
Income tax — basic & higher£17,910
Dividend tax£1,612
Capital gains tax£2,700
Income Tax, CGT & NIC due£21,062
SUPPLEMENTARY PAGES

Every supplementary page , filled and attached.

Most returns need more than the SA100. ac-co works out which supplementary pages you need from your connected data, fills them, and submits the whole bundle in a single HMRC transaction.

  • SA102 EmploymentPAYE, benefits-in-kind and tax already deducted, reconciled to your P60/P11D.
  • SA103 Self-employmentFull or short, with the right expense categories and capital allowances.
  • SA105 / SA106UK property and foreign income, with double-taxation relief where it applies.
  • SA108 Capital gainsListed shares, crypto, property and other assets — pooled and computed.
Pre-submission checks
✓Bank interest reconciled to HMRC pre-population
✓Dividend vouchers match broker contract notes
✓Crypto disposals pooled under s.104 — no wash sales
✓Section 24 finance-cost reducer applied to property
✓Expenses vs last year within expected range
!Use-of-home allowance not yet claimed
SEE IT END TO END

Watch a whole SA100 file itself — connect, draft, compute, check, submit.

A real return, start to finish, in about ninety seconds. Six steps, every figure traced to its source, ending in an HMRC acceptance receipt.

01Connect02Draft03Documents04Compute05Check06Submit
PRICING

Pay per return — only when you file.

No subscription, no per-page charge. Draft the whole thing for free; pay when you're ready to submit.

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

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

Start a return
  • ✓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
50% off until 14 January 2027

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

Start a return
  • ✓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
Accountant
Firms & multi-client
Custom

For practices filing at volume. Bulk import, multi-client console, white-label and review queue.

Talk to us
  • ✓Multi-client console
  • ✓Bulk Open Banking onboarding
  • ✓Review & approve queue
  • ✓Agent services account
  • ✓API + bordereau export
TRUST

We file in your name, so we hold ourselves to the highest bar.

ac-co is HMRC-recognised software submitting through the official API. Connections to your bank and books are read-only. Every figure traces to a source, and every receipt is stored for six years.

HMRC
recognised
UK GDPR
data resident in London
Open Banking
read-only
Read-only
default access
Human-in-loop
you tap to file
OAuth 2.1
scoped tokens
FAQ

Questions people actually ask.

Yes — and you should. ac-co drafts the whole return and shows you exactly where every figure came from, but you give final approval before anything reaches HMRC. You stay legally responsible for what's submitted; we make it fast and transparent to verify.

SA102 (employment), SA103 (self-employment), SA104 (partnership), SA105 (UK property), SA106 (foreign), SA108 (capital gains), SA109 (residence) and more — eleven in total. ac-co works out which ones you need from your connected data.

We pull disposals from supported brokers and exchanges, pool them under the s.104 rules, apply the 30-day and same-day matching, and compute the gain. The annual exempt amount is netted off and the result flows to SA108 automatically.

No. It's for anyone who has to file a Self Assessment — landlords, investors, high earners with PAYE plus extra income, people repaying child benefit (HICBC), company directors and side-hustlers. If you've got more than one source of income, it pays for itself.

Yes — ac-co is HMRC-recognised software for Self Assessment and submits directly through the official API. You get a real IRmark and receipt, the same as any agent filing.

A flat fee per return — no subscription, no per-page charge. You only pay when you're happy and ready to file. See pricing above.

FILE THIS YEAR'S RETURN

Stop dreading January. Let it draft itself.

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

31 Jan 2027 deadline · most beta returns filed in under 10 minutes
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