TR1 - How to opt for single assessment

I returned to Ireland in 2009 and am compiling the TR1 for rental income.
I'm married but would like to opt for single tax assessment, but cannot find anything about it on the form.
I'd be grateful if anyone can enlighten me.
Thanks

Single assessment means each spouse is treated separately, and there is no sharing of allowances or thresholds. It is the least favourable treatment. It has to be requested before the end of the tax year, so you are too late to claim it for 2009.
If it is separate assessment you want, that should have been claimed before April 1st 2009, for the 2009 tax year.
You should attach a covering letter to request single tax treatment for 2010, if sending in a paper form to Revenue, or phone the Registration Section if using an on-line submission.

TR1 Form

Thank you so much Gervan.