Carry forward annual pension allowance- how much?

[Sophist]

Last tax year I earned about £25k for some part time work. I put it all into a pension.

This year I'll earn £70k. I'd like to put all of that into a pension as well but obviously it's higher than the £60k annual allowance.

The allowance for last year was £40k. Can I carry forward the unused £15k allowance (£40k less the £25k I paid in)? Or does the fact that I only earned £25k last year mean there is nothing to carry forward?

You fill this years allowance, then go back 3 years and fill from there forwards, as long as you were in a pension scheme during those years.

Max you can pay in is based on what you earn THIS tax year. Keep in mind that you need to take account of the tax relief at basic rate, and also any employer contributions. If in a Defined Benefit pension scheme it is more complicated as need to know the Pension Input Amount.

If you complete a tax return you need to put details of the pension payments on the return. In the notes section give basic details of carry forward, such as:
Using pension annual allowance carry forward: £60k 2024/25, £10k 2023/24

Is there any point putting the whole lot in pension? You don't pay tax /ni on first 12.5k so no benefit to putting that part into pension?

And if you do via salary sacrifice you need to ensure you don't sacrifice to go below minimum wages.