HMRC to Pre-Populate Child Benefit Data on Self Assessment Returns From Mid-July 2026

HMRC announced on 29 June 2026 that from mid-July 2026 around 300,000 Self Assessment customers liable for the High Income Child Benefit Charge (HICBC) will have their or their partner's Child Benefit payment information pre-populated on online tax returns.

The change arrives alongside the 31 July 2026 second payment on account deadline for 2025–26 — one of the busiest weeks in the UK personal tax calendar. Pre-population aims to reduce HICBC calculation errors that have driven compliance failures and unexpected bills for higher-income families.

The High Income Child Benefit Charge claws back Child Benefit when either partner's adjusted net income exceeds £60,000 for 2025–26. The charge is tapered between £60,000 and £80,000 and equals the full Child Benefit amount above £80,000.

You must pay through Self Assessment if you already file for other reasons — self-employment, rental income, or savings interest above allowances. You can opt to pay via PAYE tax code instead if you do not otherwise need to file, but many higher earners are already in Self Assessment.

Child Benefit itself is worth up to £26.05 per week for the eldest child and £17.25 for additional children in 2025–26 — roughly £1,355 and £897 annually per child. Under-reporting the charge creates arrears plus interest.

From mid-July, eligible Self Assessment customers filing online will see Child Benefit amounts that HMRC holds pre-filled in the relevant return section. This follows HMRC's broader strategy of pre-populating returns with third-party data — similar to PAYE employment income and State Pension entries.

Taxpayers can review, amend, or delete pre-populated figures if they believe the data is incorrect before submitting. HMRC refreshes source data regularly, but mismatches can arise where Child Benefit was claimed by a partner, payments stopped mid-year, or household arrangements changed.

If you amend or delete pre-populated Child Benefit data, keep brief notes explaining why — HMRC compliance checks may ask for evidence if declared figures differ from held records.

The HICBC update does not change the 31 July 2026 payment on account deadline. Second instalments for 2025–26 are due by midnight — each payment equals 50% of your 2024–25 Self Assessment liability unless you have reduced payments on account via form SA303.

HMRC reports more than 110,000 Self Assessment payments via the HMRC app since April 2026. Payment plans can spread costs monthly or weekly, and payments made through plans count toward the July instalment.

Sole traders and landlords above the £50,000 MTD ITSA threshold should also note the first quarterly update deadline for 2026–27 falls on 7 August 2026 — one week after the July payment date.

Compare HMRC's pre-populated Child Benefit figures against your own records — bank credits from DWP and the Child Benefit award notice. If your partner claims benefit and you pay the charge, confirm the correct person's return includes the liability.

If you stopped claiming Child Benefit part-way through 2025–26 to avoid the charge, ensure pre-populated data reflects only weeks benefit was actually received. Electing not to receive payments does not remove the charge if entitlement continued.

FinnAccountings Self Assessment workflows flag HICBC exposure from household income data and reconcile pre-populated entries before submission — start a free trial to file accurately before the 31 January 2027 return deadline.