Making Tax Digital

What is MTD ITSA?#

Making Tax Digital for Income Tax Self Assessment requires sole traders and landlords to keep digital records and submit quarterly updates using compatible software.

Rollout Timeline#

Date	Who
April 2026	Income over £50,000
April 2027	Income over £30,000
TBC	Income over £20,000

HMRC API Integration#

API	Purpose	Status
Self Assessment	SA returns	Live
Obligations	Deadlines	Live
Business Income	BISS data	Live
Individual Calculations	Tax calcs	Live
National Insurance	NI lookup	Live

OAuth 2.0 Flow#

sequenceDiagram
    participant User
    participant TaxMTD
    participant HMRC
    User->>TaxMTD: Click "Connect HMRC"
    TaxMTD->>HMRC: Redirect to Gov Gateway
    HMRC->>User: Login & Authorise
    HMRC->>TaxMTD: Auth code callback
    TaxMTD->>HMRC: Exchange for access token
    TaxMTD->>TaxMTD: Store encrypted tokens

Quarterly Schedule#

Quarter	Period	Deadline
Q1	6 Apr - 5 Jul	5 August
Q2	6 Jul - 5 Oct	5 November
Q3	6 Oct - 5 Jan	5 February
Q4	6 Jan - 5 Apr	5 May
Final	Full year	31 January

Quarterly Update Payload#

Each submission includes:

{
  "totalIncome": 12500.00,
  "totalExpenses": 3200.00,
  "netProfit": 9300.00,
  "taxableProfit": 9300.00,
  "incomeTaxCharged": 1860.00,
  "nic2": 44.85,
  "nic4": 558.00,
  "totalTaxDue": 2462.85
}

Setting Up HMRC#

Navigate to Settings → HMRC
Enter your National Insurance Number (NINO)
Click Authorise → redirect to Gov Gateway
Log in with your Government Gateway credentials
Grant TaxMTD permission
View obligations under Making Tax Digital

All submissions require explicit user confirmation. TaxMTD never submits to HMRC automatically.

API#

// Check HMRC connection
const status = await $fetch('https://taxmtd.uk/api/hmrc/status')

// Get obligations
const obligations = await $fetch('https://taxmtd.uk/api/hmrc/auth')

// Get SA103 data
const sa103 = await $fetch('https://taxmtd.uk/api/hmrc/sa103')

// Store NINO
await $fetch('https://taxmtd.uk/api/hmrc/nino', {
  method: 'POST',
  body: { nino: 'QQ123456C' }
})