Employer reference number

I am retired and have multiple different PAYE reference numbers from past employments. As I am no longer working, do I leave the 'employer reference number' blank at the start of the Tax return? I have included all PAYE reference numbers on page TR7 in relation to each of my pensions.

Hi NottageJE,
If you were employed during the tax year of the Self Assessment tax return you are completing ie 6 April 2023 - 5 April 2024, then you will need to include the employment details on the tax return with the employer reference number.
If not employed during the tax year then no details to record. . 
Thank you