Hi,
The tax free threshold for pension relief is based on the individuals earned income in the tax year.
As you wife has no earned income her threshold is £3600.
She can pay in £2880 and the pension provider can claim £720 from HMRC (£2880+£720 = £3600). Your wife can pay in more than £3600 if she wants, as there is no limit to the amount you can pay in. There is only a limit on how much tax relief can be claimed.
Any amount above this threshold is chargeable to tax and must be declared in a self-assessment tax return as a pension savings tax charge.
Please see:
Pension schemes rates
Thank you