Claiming higher rate tax relief on pension contribution

I’m a higher rate tax payer and paid a lump sum of £40,000 into my pension in 23/24. My pension provider added basic rate tax relief of £10,000. I need to claim back the higher rate tax relief in my self assessment. In my previous self assessments this was calculated by adding £50,000 to my tax free allowance. This time the £50,000 has been added to my basic rate amount and the rebate amount is therefore lower. Why has this changed? As I’ve paid 40% tax on the £40,000, the tax relief should total £26,666. £10,000 has been added by my pension provider, how do I claim the remaining £16,666? If I my calculation is incorrect please could someone tell me why?

Hi,
To give you the right advice here, we would need to access your record.
Contact us by webchat or phone via Self Assessment: general enquiries to allow us to do this.
Thank you.