Method for treatment of an exhaust stream, which results from a combustion in a combustion engine, characterised by - a control of a supply of a first additive into said exhaust stream through the use of a first dosage device, wherein said supply of said first additive impacts a reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive in at least one first reduction catalyst device, arranged downstream of said first dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive, said first reduction catalyst device comprising a first multifunctional slip-catalyst (SC 1), said first multifunctional slip catalyst (SC 1) including: - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; said first multifunctional slip catalyst (SC 1) thereby primarily carrying out a reduction of nitrogen oxides NO x, and secondarily carrying out an oxidation of a residue of additive in said exhaust stream; - generation of heat through at least one exothermal reaction with said exhaust stream by use of said first slip-catalyst (SC 1) of said first reduction catalyst device, said generated heat enabling a regeneration of one or several components, through which said exhaust stream passes; - catching and oxidising of soot particles in said exhaust stream through the use of a particulate filter, which is arranged downstream of said first reduction catalyst device; and - control of supply of a second additive into said exhaust stream, through the use of a second dosage device arranged downstream of said particulate filter, wherein said supply of said second additive impacts a reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least one of said first and said second additive in a second reduction catalyst device, arranged downstream of said second dosage device. - a control of a supply of a first additive into said exhaust stream through the use of a first dosage device, wherein said supply of said first additive impacts a reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive in at least one first reduction catalyst device, arranged downstream of said first dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive, said first reduction catalyst device comprising a first multifunctional slip-catalyst (SC 1), said first multifunctional slip catalyst (SC 1) including: - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; said first multifunctional slip catalyst (SC 1) thereby primarily carrying out a reduction of nitrogen oxides NO x, and secondarily carrying out an oxidation of a residue of additive in said exhaust stream; - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; - generation of heat through at least one exothermal reaction with said exhaust stream by use of said first slip-catalyst (SC 1) of said first reduction catalyst device, said generated heat enabling a regeneration of one or several components, through which said exhaust stream passes; - catching and oxidising of soot particles in said exhaust stream through the use of a particulate filter, which is arranged downstream of said first reduction catalyst device; and - control of supply of a second additive into said exhaust stream, through the use of a second dosage device arranged downstream of said particulate filter, wherein said supply of said second additive impacts a reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least one of said first and said second additive in a second reduction catalyst device, arranged downstream of said second dosage device.