Work in Sweden for 6-12 months
When staying for at least six months, you are considered as resident in Sweden for tax purposes, and are liable for taxation in Sweden on all of your worldwide income. You must also file a Swedish income tax return.
If you stay in Sweden for at least six months, but less than 12 months, you have to apply for tax registration with the Swedish Tax Agency (Skatteverket). The Swedish Tax Agency will issue a co-ordination number which is used for people who are not or have not been registered in the Swedish Population Register. You apply by using this form Application for preliminary tax (SKV 4402)
More information is available on the Swedish Tax Agency’s website: Working in Sweden for at least six months
Income tax return
If you have been working in Sweden during the whole year or part of the previous year, you must file a Swedish income tax return. The income tax return is sent by the Swedish Tax Agency in April, to all those obliged to submit a tax return. Your tax return must be filed no later than 2 May of the year after the fiscal year.
More information is available on the Swedish Tax Agency’s website: Declaring taxes - for individuals