Filing SA while PAYE is being calculated

My PAYE tax is still being calculated. Should I wait for this to be completed before I file my SA for private work? The SA will take me into the higher tax bracket so I dont want to file if it will just make my tax at 20% or will they know how much i already owe in PAYE?

Hi
When you file your Self Assessment return, you must included your PAYE pay and tax figures. If you are unsure of the correct figures to enter, check your P60, or request them from your employer.
Alternatively, we may be able to confirm these figures - contact us by webchat or phone via Income Tax: general enquiries

Thank you