Cognitive impairment, particularly slowing of information processing speed (IPS), is prevalent after stroke. However, the link between subjective cognitive complaints (SCC) and cognitive deficit remains unclear. This study evaluated the link between SCC at three months post stroke and deficit as well as objective alterations in IPS in the first year post stroke. Patients (N = 200) and healthy controls (N = 105) took part in the COMPlaints After Stroke study (COMPAS). SCC, IPS and depression were evaluated at 3 months, 1 and 2 years post stroke. The Reliable Change Index was used to assess change in IPS in the first year post. Approximately one out of three patients showed deficit in IPS irrespective of time post stroke, while a change in IPS (N = 117) over time was relatively uncommon. SCC at three months post stroke did not predict change in IPS between three months and one year post stroke, where depressive symptoms did show a link. Cross sectional data showed a deficit in IPS in a substantial number of stroke patients irrespective of the point in time. Longitudinal data revealed a further decline in a small subgroup in the first year post stroke, which was not predicted by SCC at three months post stroke. The findings show that, irrespective of time post stroke and even when stroke is relatively mild, impairment in IPS is prevalent, but cannot be predicted by the complaints patients express. The link with depressive symptoms needs more exploration.