First British Adult Passport

[rc2018]

I am an EU citizen applying for UK citizenship on the basis of 5 years residence in the UK.
The online form requires to send proof of living in the UK for the past 5 years and this should include letter from employers, or govern departments.
Would Tax Returns for self-employed individuals or letters from firms that offered self-employed work be a suitable proof?
Would also letters of appointment from employers be ok?

Many thanks

[reen]

I sent a letter from my employer, confirming I started work with them before the beginning of the 5 year period. This was accepted.

[rc2018]

I am going to send my first application for British Passport and I have just realised that my countersignatory did not write the date in the back of the photo. I have impulsively written the date. Will I have problems because of this?