Class 1B NICs: liability: what is a PAYE settlement agreement (PSA)?
A PSA is a formal agreement between HMRC and an employer. It allows the employer to account for tax on certain expense payments and benefits in a lump sum after the end of the tax year. This means that the employer does not have to operate PAYE or return the benefits on individual forms P9D or P11D.
See NIM18030 and NIM18040 for guidance on what can be included in a PSA.