New to higher rate tax and confused!

[Williteverstopbeingcold]

In the new tax year my salary will be £52000 in England so I will become a higher rate tax payer for the 1st time. However my workplace pension contributions are 9% so I think that means I won't actually pay 40% on any of my wages? Does it mean I will have a £500 or £1000 allowance for interest on savings? Would I pay tax of 40% or 20% on any interest over this? Also if I started a SIPP or similar, I assume tax relief would still be 20% as I wouldn't have otherwise paid 40% on that cash, but a friend in the same boat says it would be 40%?
DC now too old for childcare / Child Benefit etc.
Any advice from any knowledgeable people out there very welcome! Thanks!

You will only pay the 40 pct higher rate of income tax on the part of your incomr that is over £50,571.
Tthe first 12,000 odd of income is tax free (your personal allowance for 2023/24,) then it's 20 pct on income from £12,571 to £50,571 then 40 pct on the rest. (Till you get to the 45 pct rate).
And I think your persion contributions, if any, come off your gross income, reducing your tax bill further.

Your personal savings allowance will be £500 regardless of any salary sacrifice you are taking part of.

then you will be taxed 20% of interest over £500 earned. You will need to complete a self assessment including any interest you have earned.

Your pension contributions will bring you back under £50k so you will be taxed at 20%