VeriSign, Inc. announced back in July that they would be raising feed for .com and .net domain names effective January 15th 2012. The registry fee for .com domain names will increase from $7.34 to $7.85 and that the registry fee for .net domain names will increase from $4.65 to $5.11. That means that your registrar will be raising price to you. The new prices are likely to be between 50 cents and a dollar higher, and they may vary depending on the tier of service you are on. If you own 1,000 domains you can save at least $500 by renewing your domains before the January 15th deadline.
You should also read any email announcement closely. For a time I had an account with an eNom reseller which routinely raised their rates at least 2 weeks ahead of eNom and Verisign’s actual date. If your budget allows it, renew soon!