It varies, if it is registered before 1 March 2001, the rate of the vehicle tax will be based on the engine size. Since Vauxhall Vivaro Combi 2900's engine is 1995 cc, its 12 months rate will be £235.00 while its 6 months rate will be £129.25.
However, if it is registered on or after 1 March 2001, the rate of vehicle tax will be based on fuel type and CO2 emissions. And since its official CO2 Emission is 202 g/km, it will fall under band "K" (includes cars with a CO2 figure over 225 g/km but were registered before 23 March 2006), its 12 months rate will be £295.00 while its 6 months rate will be £162.25.
For further enquiries you can also contact DVLA Vehicle Registration and Tax enquiries on 0300 790 6802, available Monday to Friday from 8am to 7pm, and Saturday from 8am to 2pm. Call charges may vary.
Find out the tax rate for all vehicle types at Gov.uk.