Benefit in Kind on Health Insurance- advice please

Can someone tell me how much BIK i pay each month please? My partners health insurance is on my policy and we are trying to work out how much I pay for him each month?
My gross salary is 4485 per month, and underneath this is says medical insurance BIK 259.78 so i know i get taxed on these combined but does anyone know how much i'm actually paying?
Thank you in advance for your help

It's taxed at the marginal rate, so in your case likely 49.5% of 259.78 which is 128.59. Half that for your partner's part of it. Not sure if your claiming it already but you can claim medical insurance premium tax relief of up to 200 per adult, get onto Revenue about it if you don't have it already.

My spreadsheet is showing this for 'with BIK' vs 'without BIK' (assuming that you're receiving standard tax credits and are class A for PRSI):

So roughly the cost to you is 3062 - 3208 = 146 per month. However you get 200 a year back from revenue credits. Divide by 12 to get 17 per month. So the actual cost to you is ~130. If you want half from your husband he should pay you 65 a month.

Slight correction to elcato's figures:

3208-3082 = €126 per month or €63 per adult (assuming 2 adults only).

Then deduct ~ €17 per adult per month for the tax relief to give a net cost of €46 per adult per month.