UK Self Assessment From Scratch — Part 8: After You File

Quick answer

After you submit your Self Assessment return, here's what happens in order:

1. Confirmation email within minutes.
2. Tax calculation generated automatically — visible in Government Gateway.
3. Balance due or refund owed confirmed.
4. Payment (you to HMRC, or HMRC to you) settles by 31 January.
5. HMRC reviews during the 12-month enquiry window.
6. Records retained for 5 years post-deadline.

This is the final part of our Self-Assessment From Scratch series:

• Part 1: Do you need to file?
• Part 2: UTR and Government Gateway setup
• Part 3: Declaring every type of income
• Part 4: Allowable expenses
• Part 5: Capital gains
• Part 6: Payments on account
• Part 7: Making Tax Digital
• Part 8: After you file ← you are here

Getting your refund

If HMRC owes you money (overpaid tax, payments-on-account refund, Marriage Allowance backdating):

Speed by payment method

• BACS to bank account: 5-10 working days (fastest, recommended).
• Cheque to home address: 14-21 days.
• Refund applied to next year's tax: instant, but you don't see the money.

How to ensure BACS

Log into Government Gateway → Self Assessment → "Refunds" → add bank account details (sort code + account number). HMRC verifies the account name against your registered name automatically.

If you don't add bank details, HMRC defaults to a cheque, which is slower and easier to lose in the post.

Refund status tracking

The HMRC app shows refund status:

• "Approved" — your return is processed.
• "Issued" — payment sent.
• "Cleared" — money should be in your account.

Most refunds clear within 5-7 working days for established accounts.

When refunds get held up

• Identity verification triggered — usually a one-off security check, resolved by phone or app verification.
• Bank account name mismatch — name on HMRC record ≠ name on bank account.
• HMRC enquiry pending — refunds can be held during an enquiry.
• Other debts owed to government (council tax, child maintenance via DWP) — HMRC can offset.

Paying a balance owed

If you owe HMRC money after the return, pay by 31 January (the same deadline as filing).

Payment options

Use payment reference: [your UTR]K (e.g. 1234567890K). The K tells HMRC the payment is for Self Assessment.

Time to Pay if you can't afford it

HMRC's Time to Pay arrangements:

• Under £30,000: set up online, no phone call needed.
• Over £30,000: call HMRC (0300 200 3835 SA helpline).
• Up to 12 instalments typically.
• 7.5% interest still accrues throughout.
• Late-payment penalties waived if arrangement agreed before deadline.

This is dramatically better than missing the deadline. Set up before 31 January if you can.

Amending a return

Made a mistake? You can amend within 12 months of the original 31 January deadline.

How to amend

1. Log into Government Gateway → Self Assessment.
2. Find the relevant year's return.
3. Click "Amend a return".
4. Make changes and resubmit.

The new return supersedes the original. HMRC processes within a few weeks. If you owed more, a balancing payment is added; if you overpaid, a refund issued.

Material errors after 12 months

If you find a serious error after the 12-month amendment window:

• Overpayment relief — claim within 4 years of the end of the tax year. Send written claim with evidence.
• HMRC enquiry — if HMRC opens an enquiry into your return, you can correct during that.

HMRC enquiries

HMRC has 12 months from submission to open an enquiry into a normal return. Longer windows apply for:

• Careless errors: 6 years.
• Deliberate underdeclaration: 20 years.

Types of enquiry

1. Random check — about 1 in 50 returns are sampled. Often results in no change.
2. Targeted check — based on risk indicators (large drop in profit, unusual expense ratios, missing income types).
3. Whistleblower / data match — HMRC's data matching identifies discrepancies (bank interest reports, crypto exchange data, eBay platform reports).

What an enquiry looks like

1. HMRC letter opens the enquiry — usually states which year and what's being questioned.
2. Information request — receipts, bank statements, working papers.
3. Meetings or correspondence with HMRC officer.
4. Findings issued — usually within 6-12 months.
5. Outcome:
   • No change.
   • Adjustment + interest at 7.5%.
   • Penalty (careless: 15-30%, deliberate: 35-100%).

Responding to an enquiry

• Don't ignore HMRC letters. Failure to respond escalates.
• Get accountant or tax advice for non-trivial enquiries.
• Be honest — material concealment can convert a careless penalty into deliberate (100% of tax).
• Provide requested information within the deadline (usually 30 days).
• You can appeal decisions you disagree with — first internally, then to a tribunal.

The SA302 — your tax calculation summary

Mortgage lenders, immigration applications and many other processes want proof of your self-employed income. The SA302 is HMRC's official summary.

How to get one

1. Log into Government Gateway.
2. Self Assessment → "View your returns".
3. Select the relevant year.
4. Click "Tax calculation" — opens the SA302 PDF.
5. Download/save.

You can request SA302s for the last 4 tax years. They're free and instant.

Most UK mortgage lenders accept the online SA302 (printed from your Government Gateway). A few traditionalists demand the postal version from HMRC — call 0300 200 3310 to request, takes 7-10 days.

Lenders typically want 2-3 years of SA302s plus matching Tax Year Overviews (which show payments to HMRC).

Record-keeping requirements

HMRC requires you to keep records for 5 years after the 31 January submission deadline.

So for 2025/26 (filed by 31 January 2026):

• Records retained until 31 January 2031.

What to keep:

• All income evidence — invoices, bank deposit records, dividend vouchers, P60s, P11Ds.
• All expense evidence — receipts, invoices, mileage logs, professional fee receipts.
• Bank statements for the period.
• Tax software exports if used.
• Communications with HMRC.

Digital scans are acceptable — you don't need paper. Cloud storage (Dropbox, Google Drive) counts. Just ensure the records are recoverable for 5 years.

What happens next year

Once you've filed, HMRC automatically expects you to file the following year's return too. The cycle:

• 6 April 2026: new tax year (2026/27) begins.
• Throughout 2026/27: you keep records (or use MTD ITSA if applicable).
• 5 April 2027: tax year ends.
• By 31 January 2028: file 2026/27 return and pay any balance.

To stop being in Self Assessment, you must tell HMRC explicitly. You can:

• Phone HMRC (0300 200 3310) with your UTR and explain.
• Or via Government Gateway → Self Assessment → "Tell HMRC you don't need to file".
• HMRC removes you from the next year onwards.

Common reasons to stop:

• Closed your business / no longer self-employed.
• Now PAYE-only with no other income triggers.
• Retired with income below thresholds.

The end of the series

That completes our 8-part Self-Assessment From Scratch series. Together:

• Part 1: Do you need to file?
• Part 2: UTR and Government Gateway setup
• Part 3: Declaring every type of income
• Part 4: Allowable expenses
• Part 5: Capital gains
• Part 6: Payments on account
• Part 7: Making Tax Digital
• Part 8: After you file ← end

You should now have a complete picture: who needs to file, how to register, what to declare, how to claim expenses, how CGT works, how payments on account work, what MTD will change, and what happens after you submit.

For specific calculation help across all of this:

Sources

• HMRC: After you've sent your tax return
• HMRC: Claim a tax refund
• HMRC: Self Assessment: appeals and reviews
• HMRC: How to get evidence of your earnings (SA302)
• HMRC: Compliance checks
• HMRC: Time limits for assessing or correcting tax returns