I work full-time but am currently doing a nixer for a prior employer. They are insisting on an invoice but obviously I am not charging VAT. Am I foolish to supply one - could this backfire on me?
If you supply an invoice you cannot charge vat as you are not registered to do so. If you supply an invoice your former employer will include it when making their accounts and if they are subject to a Revenue Audit it will be followed up.
My advice is supply an invoice and return details on your tax return for 2008.
When filing the income remember that you may deduct any expenses actually incurred in doing the job from the income and file the net income which is then subject to tax and possibly PRSI/Levies.
If they put you back on the payroll you can't claim expenses as a deduction. Employer maynot be inclined to do this as he will be liable for employer PRSI.