Hi ... I speak from experience of having had to complete the paperwork and pay the tax!!
Andalucia ... for residents and that includes spaniards born & bred there is an exemption between spouses on the marital home.
It is 99.9% of the inherited amount after the deduction of the 15.956,87 euro allowance but only UPTO a limit of 122,606,47 euro.
The value of the property is the official value .... ie the catastral value multiplied by a 'coeficiente' published by the government.
For me in Mijas Costa that was 2.0
This tax is 'self-assessment' and the authorities then have 4 years in which to challange the amount you have declared and paid.
It is best to pay for the services of a lawyer/gestoria that specialises in this type of taxation ... they know all the nooks and crannies in the law and should be able to make a stressful time a little easier.
DO NOT forget that there has to be a spanish will directing who should inherit the assets .... NO WILL means forced inheritance takes place.......... ie ... wife will not necessarily get the house/money/dog etc
For non-residents I THINK (but not certain) there are no allowances or exemptions
There are areas in Spain where the Inheritance tax is at 0% ... so effectively nothing to pay - perhaps we should all move there!
PS I understand that the period after which inheritance tax cannot be claimed by the authorites is 6 years....BUT!!