The deadline for filing the 2017/18 P11D is 6 July 2018.

The deadline for payment of Class 1A NICs for 2017/18 is 19 July, or 22 July, if paid electronically, unless you have ceased trading.

Useful links:

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 requirement to report expenses