The whole idea of SIPs is that you should be systematic with your investments. When you step up your SIPs for a limited period, this is not being systematic. You may actually end up investing more at a market high. If you have some extra money to invest, just spread it over a period of time. For instance, if you have received an annual bonus, spread it over six months. If you have got a sizeable amount on selling an asset, spread it over the next three years. How you deploy your windfall is determined by two factors: how crucial it is and how large the amount is.