The deadline for filing the 2020-21 P11D is 6 July 2021.

The deadline for payment of Class 1A NICs is 19 July, or 22 July, if paid electronically, unless you have ceased trading.

Useful guides on this topic

Tax penalties: P11Ds
Penalties for late filing and incorrect returns

Do ALL directors need to complete a P11D?
Guidance for employers

PAYE: P11D dispensations
Opt-in for employers in order to reduce the requirement to report expenses