All things being equal, as disposal income increases, consumption and savings increase. The relationship between disposable income and consumer expenditure is called 'the consumption function '. This positive amount of consumption without any disposable income is called autonomous consumption . Thus as disposable income increases so does savings. Net taxes equal taxes minus transfers to households by government.
Net taxes tend to increase as real GDP or income increases, e.g. income tax.
Thus changes in MTR will shift the slope of consumption curve. The relationship between disposable income and saving is called the savings function. Such changes can shift the consumption and savings functions. Expected real profit rate equals the monetary profit rate minus the inflation rate. All things being equal, the higher the real profit rate the higher the level of investment.